BBC
Mrs Clinton says she is "quite hopeful" that reforms undertaken by the government could lead to a broader "movement for change".
She is due to meet Nobel laureate Aung San Suu Kyi and President Thein Sein on her two-day visit.
No US politician of her seniority has visited since an army takeover in 1962.
Burma has been largely isolated since then, under an autocratic and unpredictable military regime.
The military oversaw elections last year that transferred power to a military-backed, nominally civilian government.
But the new government under Thein Sein - a former general - has undertaken some steps towards reform.
'Flickers of progress'
Mrs Clinton landed in the remote capital, Nay Pyi Daw, on Wednesday afternoon. She will meet top officials on Thursday before heading to Rangoon to meet pro-democracy leader Aung San Suu Kyi.
Earlier, she told reporters in South Korea that she wanted to see for herself how committed the government was to change.
The government has made efforts to reform election laws and rules banning protests. It has also released some political prisoners.
The changes have been rewarded by regional group Asean, which has agreed to allow Burma to take the chairmanship of the bloc in 2014.
And Ms Suu Kyi's National League for Democracy has re-registered as a political party.
The NLD had operated outside the political system for two decades, and Ms Suu Kyi spent much of that time in detention.
It boycotted the polls last year because of laws that prevented Ms Suu Kyi and other senior pro-democracy leaders from running.
These laws have now been changed and the party says it will field candidates in a forthcoming by-election for seats in parliament left empty by the appointment of ministers.
However, critics say that the country still holds hundreds more political prisoners, and that fierce fighting is continuing between government troops and ethnic insurgents in several states.
Hillary Clinton's plane landed at the airport in the remote capital Nay Pyi Daw
US Secretary of State Hillary Clinton has arrived in Burma on the first visit by such a senior American diplomat in 50 years.
She is due to meet Nobel laureate Aung San Suu Kyi and President Thein Sein on her two-day visit.
No US politician of her seniority has visited since an army takeover in 1962.
Burma has been largely isolated since then, under an autocratic and unpredictable military regime.
The military oversaw elections last year that transferred power to a military-backed, nominally civilian government.
But the new government under Thein Sein - a former general - has undertaken some steps towards reform.
'Flickers of progress'
Mrs Clinton landed in the remote capital, Nay Pyi Daw, on Wednesday afternoon. She will meet top officials on Thursday before heading to Rangoon to meet pro-democracy leader Aung San Suu Kyi.
Earlier, she told reporters in South Korea that she wanted to see for herself how committed the government was to change.
"We and many other nations are quite hopeful that these flickers of progress... will be ignited into a movement for change that will benefit the people of the country," she said.
The changes have been rewarded by regional group Asean, which has agreed to allow Burma to take the chairmanship of the bloc in 2014.
And Ms Suu Kyi's National League for Democracy has re-registered as a political party.
The NLD had operated outside the political system for two decades, and Ms Suu Kyi spent much of that time in detention.
It boycotted the polls last year because of laws that prevented Ms Suu Kyi and other senior pro-democracy leaders from running.
These laws have now been changed and the party says it will field candidates in a forthcoming by-election for seats in parliament left empty by the appointment of ministers.
However, critics say that the country still holds hundreds more political prisoners, and that fierce fighting is continuing between government troops and ethnic insurgents in several states.
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