The heavy rain in the Kyushu region, southwestern Japan, started over the weekend, causing deadly flooding and mudslides.
Authorities in Kumamoto Prefecture say 44 people have been confirmed dead, one is without vital signs, and 10 others are missing.
Fourteen of the victims were found at a nursing home near the Kuma River.
A footage from a viewer in Kagoshima Prefecture shows flooded roads and water flowing out of storm drains. Firefighters in the area say they have received several rescue requests from residents.
In the city of Minamisatsuma, police say a man in his 60s is missing after leaving his house to deliver newspapers.
Another viewer in Fukuoka Prefecture took a video of what he says is a rice field, which was flooded by an overflowing irrigation channel.
Another video one shows the water level on a river in Nagasaki Prefecture almost reaching the danger zone for flooding on Monday afternoon. The man who recorded it says the water level rose about one meter in just ten minutes.
Prime Minister Abe Shinzo instructed officials to do all they can to save lives and support those who have been affected. He called on people across Japan to be on alert, and to get the latest information from local governments.