Abstract: A reinforcement layer of a high-pressure vessel has a plurality of low helical layers. In at least one of the (i?1)-th low helical layer and the i-th low helical layer, the difference between the diameter of an opening formed in an end portion of the (i?1)-th low helical layer and the diameter of an opening formed in an end portion of the i-th low helical layer is equal to or larger than the width of the band-shaped fiber when an inclination angle WA of the band-shaped fiber is equal to or smaller than a second angle smaller than a first angle.

Abstract: A high-pressure tank is provided with a liner made of resin, a reinforcing layer including a plurality of fiber layers formed by winding fiber a plurality of times around the outer surface of the liner, and a cap fixed to the axial end portion of the liner and including a supply and discharge hole that supplies and discharges fluid to and from the liner. A starting end, which is a start of winding of the fiber, is disposed overlapping the cap.

Abstract: A reinforcement layer of a high-pressure vessel has a plurality of low helical layers. In at least one of the (i?1)-th low helical layer and the i-th low helical layer, the difference between the diameter of an opening formed in an end portion of the (i?1)-th low helical layer and the diameter of an opening formed in an end portion of the i-th low helical layer is equal to or larger than the width of the band-shaped fiber when an inclination angle WA of the band-shaped fiber is equal to or smaller than a second angle smaller than a first angle.