This paper describes an Ar+ laser used for measuring MBD60 for the skin of the yellow race. The skin erythematous reaction threshold level at 488.0 nm and 514.5nm for two groups of volunteers are measured. The skin of the volunteers is exposed to the above energy densities, and histological examination finds that capillaries are expanded and filled with erythro-cytes and light edema, but there is no significant change of the cuticle.