0750 GMT July 19, 2018
Prime Minister Shinzo Abe visited an evacuation center in the city of Kurashiki in Okayama prefecture, where more than 40 of the 176 victims died, AP reported.
The prime minister and his government pledged an initial $4 billion towards relief efforts on Tuesday, and have offered an additional special budget if needed.
Tens of thousands of rescue and recovery workers and volunteers were searching for people still missing.
Record rainfall began last Thursday and continued over the weekend, pounding western and central prefectures. Officials said at least 176 people have died and dozens more are still missing, Reuters reported Wednesday.
Authorities have warned that new landslides could be triggered by thunderstorms and intensifying heat gripping the country.
This is the highest death toll caused by rainfall that Japan has seen in decades.
Authorities on Sunday ordered evacuations for up to 5.9 million people in 19 nearby prefectures, The Japan Times reported. 30,000 people had taken refuge in evacuation centers on Sunday afternoon, according to Japan's Fire and Disaster Management Agency, Reuters reported.
Residents shoveled mud and debris to clear streets so they could get out for food and other supplies Wednesday in areas of western Japan hard hit by landslides and flooding that still swamped some areas.
In areas where search-and-rescue operations had ended, construction workers and residents worked in neighborhoods to clear mud and debris and restore vehicle access to the outside and get supplies and food.
Most of the deaths were in Hiroshima and the surrounding area, but the damage was widespread.
The government has mobilized 75,000 troops and emergency workers and some 80 helicopters for the search and rescue effort, Chief Cabinet Secretary Yoshihide Suga said.
Delivery companies Sagawa Express Co. and Yamato Transport Co. and cargo service Japan Freight Railway Co. said some of their shipments to and from the flooded areas have been suspended or reduced. Supermarkets have closed stores or shortened hours due to delivery delays and supply shortages.
Thousands of homes were still without clean water and electricity. Residents lined up for water under a scorching sun as temperatures rose to 35 Celsius (95 Fahrenheit), raising the risk of heat stroke.
Suga said earlier the government was spending 2 billion yen ($18 million) to hasten deliveries of supplies and other support for evacuation centers and residents.
Abe canceled a planned trip to Europe and the Middle East this week to oversee the emergency response.