PURPOSE: To improve the washing efficiency of wash with the rotary washing machine which has an outside cylinder and an inside cylinder rotating its horizontal axis within this outside cylinder and is constructed to put the inside cylinder in a half immersed state in the inside cylinder put into the outside cylinder and to rotate the inside cylinder.

CONSTITUTION: Problems are solved with this rotary washing machine by setting the direction of a ridge or fin-shaped beater 10 disposed on the inner peripheral surface of the inside cylinder 6 at the direction intersecting diagonally with a revolving shaft 7 of the inside cylinder 6 and changing the projecting height H to the inner peripheral side of the beater 10 in the axial direction of the revolving shaft 7 of the inside cylinder.