TANK DEVICE

A filter element is allowed to be replaced from a side surface of a tank. A return filter and a strainer are provided sideways inside the tank that is a cavity. The tank has two substantially parallel side surfaces, a tank first side surface and a tank second side surface, and the return filter is provided in the tank via an insertion hole formed in the tank first side surface. The strainer has one end provided on an outflow portion provided on a bottom surface of a filter case and the other end provided on the tank second side surface.