Soldiers raised the national flag at 4:28 am (2148 GMT) -- the exact time of the country's freedom from Britain -- at a city hall in the remote capital of Naypyidaw, 400 kilometres (250 miles) north of Yangon.
In comments read out by a subordinate in the bunker-like capital, Senior General Than Shwe trumpeted his seven-step "Road Map" to democracy, which the junta says will lead to multi-party elections next year.
He urged people to "cooperate in realising the state's seven-step Road Map with union spirit and patriotic spirit with the firm resolution to build up a peaceful, modern and developed democratic nation with flourishing discipline".
Than Shwe accused "neo-colonialists" -- usually a reference to the United States -- of interfering in Myanmar's affairs.
"The entire people are duty-bound to safeguard the motherland... while keeping a watchful eye on attempts of neo-colonialists to harm the sovereignty of the country," Than Shwe said.
About 3,000 ministers, government employees and senior officials attended the ceremony and the formal military parade, although the ageing Than Shwe was not present.
The United States, European Union and United Nations have dismissed the lengthy "Road Map" as a sham due to the absence of detained opposition leader Aung San Suu Kyi's National League for Democracy (NLD) party.
Myanmar pro-democracy activists say the polls are aimed at cementing the military's grip on the nation, with Aung San Suu Kyi banned from running and 25 percent of parliament seats reserved for members of the armed forces.
Myanmar has been ruled by the military since 1962, despite a 1990 election win by Aung San Suu Kyi and her NLD. Instead of allowing her to take office, the military regime simply kept her under house arrest.