PURPOSE: To manufacture a door easily and to make it possible to finish corners of both side edges beautifully by providing bending sections along corners of the width direction of the door to the surface members stuck on the fronts and rears of cores, and providing the butt ends to the front ends of the bending sections.

CONSTITUTION: Surface members 30 and 30 are respectively stuck on the fronts and rears of cors 20-22 to form a door 10. Bending sections 31... bent in the direction of the inside and outside in the thickness of the door 10 along corners positioned to both ends widthwise of the door 10 are provided to the surface members 30. In addition, Butt ends 32... to butt at the approximate center in the direction of the thickness of the door 10 are provided to the front ends of the bending sections 31. Notch sections having a V-shaped section are formed to the insides of the bending sections 31 of the surface members 30 lengthwise of the door 10, and the butt ends 32 of the surface members 30 are folded inward from the notch sections. According to the constitution, end closures of both corners of the door 10 can be omitted.