[Problems to be Solved] It is intended to provide a washing method for reliably cleaning water-soluble contaminations such as sweat without damaging fabrics.[Solution] A frame body 18 is disposed horizontally in a casing. The frame body 18 is rotated by a drive motor 23 in the casing. The casing and the frame body 18 are filled with water, and then clothes are placed in the frame body 18. A plurality of protrusions 40 are formed in order that an inner periphery 39 of the frame body 18 has a wavy pattern. A height of the protruding parts is set to from 3.0% to 6.0% of an inner diameter of the frame body 18. A surfactant contained in a cleaning liquid permeates deep into clothes.