A heating cooker includes: a top plate on which a cooking container to be heated is placed; an outer case as a main body having an upper surface on which the top plate is placed; a heater heating the cooking container; and a light emitting device disposed in the outer case, for displaying the heating state. The top plate includes: a glass substrate having a transparent light-transmitting low-expansion crystallized glass made mainly of Li2O—AL2O3—SiO2 and having β-quartz solid solution, having a crystal size smaller than the wavelength of visible light; a design layer having a black-based color disposed on an undersurface of the glass substrate; a diffusion region disposed partially on an undersurface of the design layer, for diffusedly emitting light from the light emitting device; and a light-blocking layer disposed on the undersurface of the design layer other than the diffusion region, for blocking light from below.