Authorities fear the numbers will grow as rescue operations continued.
Around 3,000 policemen, firemen and troops of the Self-Defence Forces (SDF) are searching for people swept away in rivers and canals, landslides or mud flows.
Rescue operations had to be suspended Thursday as heavy rain in the region threatened to cause more landslides.
Japan Meteorological Agency (JMA) has predicted further torrential rain and storms in the same area and other parts of the country between Friday and Saturday.
On Wednesday, Hiroshima received record rainfall, equivalent to precipitation for the entire month of August in the mountainous region.
The floods have destroyed 46 houses and caused serious damage to 139 others in the region, where a thousand people have already been evacuated, the Kyodo news agency reported.
Aerial photos of the region show the devastation caused by mud slides in 31 different areas of Hiroshima, where 20 people died in 1999 in similar torrential rains.