A cleaning method for an extreme ultraviolet light reflection mirror includes a contacting step of bringing α-tin into contact with solid tin debris attached to an extreme ultraviolet light reflection mirror and an aging step of leaving the tin debris brought into contact with the α-tin in a temperature environment below a freezing point to promote turning into tin pest of the tin debris. The cleaning method further includes a removing step of removing the tin debris turned into tin pest from the extreme ultraviolet light reflection mirror.