The junta’s previous death toll was 33, with more than 235,000 people displaced, according to figures released on Friday.
Swathes of farmland have been inundated in central regions, including around the sprawling, low-lying capital Naypyidaw.
There have been reports of landslides in hilly areas but with roads and bridges damaged and phone and internet lines down, compiling information has been difficult.
The floods have heaped more misery on the country where war has raged since the military seized power in 2021.
More than 2.7 million people were already displaced in Myanmar by the conflict.
Myanmar’s junta chief made a rare request for foreign aid to deal with the floods, state media reported on Saturday.
The military has previously blocked or frustrated humanitarian assistance from abroad.
Last year it suspended travel authorisations for aid groups trying to reach around a million victims of powerful Cyclone Mocha that hit the west of the country.
