A lids for a child’s drinking cup has a projection extending integrally from an underside of the lid, the projection defining, in an upper surface of the lid body, a straw receptacle. Production of the output signal is initiated at a time determined by a timing signal and is completed at a time which is delayed by a delay time with respect to said timing signal. The plurality of light source sections for detection has a first light-emitting element, and a second light-emitting element located closer to the light detection section side than the first light-emitting element.