PURPOSE: To save labor for separately preparing any light every time of flickering that light in the case of cutting wedding cake by irradiating the wedding cake with light from the blade body itself of the knife for wedding cake.

CONSTITUTION: This knife is provided with a blade body 4 composed of a transparent or translucent material almost as a whole and a grip body 6 equipped with an electric lamp housing part 3 for incorporating an electric lamp 2 inside and a switch operating part 5 for controlling the switch-on/off of the electric lamp 2 housed in the electric lamp housing part 3, and the entire blade body 4 can be irradiated with the light from the electric lamp 2 housed in the electric lamp housing part 3 through an opening window 7 provided at the front end of the grip body 6.