that measures friction under dynamic conditions with constantly-changing velocity has been developed and is attracting attention 9−12) . This system can evaluate frictional phenomena on short timescales at the beginning of motion, velocity dependence of frictional force over a wide range, and hysteresis that reflects dependence on forces previously applied to an object. In addition, we used the system to evaluate the frictional force of foam composed of a surfactant aqueous solution. We observed a hydrodynamic stable pattern in which the friction force increased as a function of the velocity, without any static friction 13) . The foam was lubricious, less dependent on the vertical force, and more durable to mechanical stimuli in the thickeneradded system.In this study, the foams of commercial body cleansers were assessed using a sinusoidal-motion friction evaluation system: the frictional force of the foam between two acrylic plates was measured when the foam was rubbed under sinusoidal motion, and the shape of the foam was observed using a microscope. The viscosity of the cleaning agents and porosity of the foams were evaluated to determine their effect on the frictional force.