All developed country looking forward with blockchin technology with overcoming draw back of bank system.
Many financially developed countries are friendly toward bitcoin, the peer-to-peer digital currency that was developed in the wake of the 2008 financial crisis.

Read more: 5 Most Bitcoin Friendly Countries | Investopedia https://www.investopedia.com/articles/forex/121715/5-most-bitcoin-friendly-countries.asp#ixzz5KMlVycFp
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Big whales already involved in the upgradation of technology, Daytoday every one is talking about technology.
New revolutionary upcoming technology is Blochchin Technology on basis of block chin Bitcoin is running as currency

We will talk later on block chin and Atlcoins later on. Now lets see which country using Bitcoin as payment system.

US :-
Top one bitcoin-friendly country in the worldThe first regulations were issued by the Financial Crimes Enforcement Network (FINCEN) in March 2013, putting digital currency exchangers and processors under the Banking Secrecy Act by defining them as money service businesses. This means the companies must comply with a range of registration and record-keeping requirements consistent with other financial institutions.

classified bitcoin as a convertible decentralized virtual currency in 2013, The Commodity Futures Trading Commission,CFTC,classified bitcoin as a commodity in September 2015. Per IRS, bitcoin is taxed as a property.
In September 2016, a federal judge ruled that "Bitcoins are funds within the plain meaning of that term"

In hotels accepted as payments and Bitcoin atm available.

Japan :-
We all are very familiar with Mt. Gox scam and bankruptcy this oldest exchange from Japan, he allows us to trade the Bitcoins. Mt. Gox erupted in February 2014 has led to calls for the introduction of a regulatory structure. This is likely to include a sharp reduction in the anonymity of transactions and rules to prevent money laundering. Regulations are expected to be introduced early in 2016.

the Japanese government, in response to a series of questions asked in the National Diet, made a cabinet decision on the legal treatment of bitcoins in the form of answers to the questions.The decision also acknowledges that there are no laws to unconditionally prohibit individuals or legal entities from receiving bitcoins in exchange for goods or services. Taxes may be applicable to bitcoins.

Canada:-
In November 2013, the Canada Revenue Agency declared that Bitcoin payments should be treated as barter transactions. The Canadian federal government also announced its intention to regulate Bitcoin through its anti-money laundering and counter-terrorist financing legislation.

The Authorite des Marches Financiers, the regulator in the province of Quebec, has declared that some bitcoin related business models including exchanges and ATMs are regulated under its current MSB Act.

The Canadian Senate recommended it remain that way. With a new Liberal government having taken office in November 2015, however, it remains to be seen if that may change. The currency's popularity in the country has been uneven. The first bitcoin ATM was installed in Vancouver in October 2013, allowing people to trade between Canadian dollars and bitcoin. But in 2015, two major exchanges went out of business. This was followed by the announcement that one of the country's largest pension funds, the Ontario Municipal Employees Retirement System, was considering making investments in bitcoin and related startup businesses

Philippines :
In February 2017, BSP the Philippine Central Bank said it plans to officially regulate local Philippine Bitcoin exchanges as remittance companies and recognize Bitcoin as a legitimate payment method, while issuing a proper regulatory framework for Bitcoin users, exchanges and companies.

Planning for the includes Bitcoin, other digital currencies an in cards for better use in the future, exchanges are expanding their area and security on regularly basic with upgrade technology.

European Union:-
Bitcoin has been relatively free of regulation in the European Union and received a major boost from an October 2015 court decision that exempts transactions with the digital currency from value-added tax (VAT). This puts Bitcoin in line with transactions in other currencies. However, in the aftermath of the Nov. 13, 2015, terror attacks in Paris, there have been widespread calls for a crackdown on anonymous forms of payment. This includes Bitcoin, other digital currencies and prepaid debit cards. Legislation regarding this is expected to be introduced in the European Parliament early in 2016.

Australia:-
Removing Bitcoins from double taxation policies, the government also legalized Bitcoin and said it can be used just like money. This country is so much in the favore of bitcoin also there thought is to include altcoins.
Bitcoin is legal. Although not considered to be an official form of currency, earnings are subject to tax law.

Thailand:
When first time I know am shocked such small country is going with great technology and accepting the bitcoins.

In 2013, the Thai central bank declared the use of Bitcoin illegal in Thailand, but changed its opinion in early 2014 to make it not illegal. However, buying Bitcoin in Thailand and then selling it outside the country was still strictly prohibited.

UK :-
The Bank of England continues to monitor Bitcoin technology, while it continues to be classified as private money, with VAT applied and also subject to capital gains tax, where there P&Ls are involved.

As of 2017, the government of the United Kingdom has stated that bitcoin is unregulated and that it is treated as a 'foreign currency' for most purposes, including VAT/GS. Bitcoin is treated as 'private money'. When bitcoin is exchanged for sterling or for foreign currencies, such as euro or dollar, no VAT will be due on the value of the bitcoins themselves. However, in all instances, VAT will be due in the normal way from suppliers of any goods or services sold in exchange for bitcoin or other similar cryptocurrency. Profits and losses on cryptocurrencies are subject to

Now am going put only name of Country which are supporting Bitcoin :

Brazil
Bulgaria
Chile
Colombia
Croatia
Czech Republic
Denmark
Estonia
Finland
Germany
Ireland
Israel
Italy
Malaysia
New Zealand
Poland
Singapore etc.

This post is ref from www.google.com (Different other sites).