Yoshihide Suga said search operations were continuing after the worst weather-related disaster in Japan in over three decades.
Prime Minister Shinzo Abe, who visited one of the worst-affected regions on Wednesday, plans to travel Friday to another area hit by deadly flooding and landslides after the rains, Suga said.
Abe cancelled a four-stop foreign trip due this week as the death toll in the disaster rose.
Hopes for finding survivors have faded a week after the rains began, even though the downpours have now stopped and flood waters have receded.
At least 10,000 people who evacuated their homes or were rescued are now living in shelters, and the government has pledged to set aside emergency funding to help people return home.
"We will do everything we can so that people will not have to continue living in uncomfortable situations in shelters," Abe said at a morning meeting.
More about: #Japan