Patent ID: 8732929

Claim:
A manufacturing method of a gas tank, comprising the steps of: coupling a connecting part of a rotating shaft to a mouthpiece attached to an end of a tank main body in its axis direction, the connecting part having an outer circumferential surface which continues smoothly to an outer circumferential surface of the mouthpiece; winding a fiber around over an outer circumferential surface of the tank main body, an outer circumferential surface of the mouthpiece and a part of an outer circumferential surface of the connecting part, while rotating the tank main body by the rotating shaft, to form an outer circumferential layer on the outer circumferential surface of the tank main body, the outer circumferential surface of the mouthpiece and a part of the outer circumferential surface of the connecting part; and detaching the connecting part of the rotating shaft from the mouthpiece to form, on an end of the tank in the axis direction, a recess section in which an outside end surface of the mouthpiece in the axis direction is embedded in an inner side from an outside end surface of the outer circumferential layer in the axis direction.