PURPOSE: To reduce weight, and enhance reliability excellent at falling impact by arranging an inner shell having gas barrier performance and an outer shell having withstand voltage performance, and forming its outer shell of CFRP by reinforcing resin by carbon fiber having tensile strength not less than a specific value.

CONSTITUTION: A gas cylinder 1 is provided with an inner shell 2 having gas barrier performance and a lightweight outer shell 3 having withstand voltage performance to cover its inner shell 2. An FRP-made reinforcing layer 7 by compounding resin and woven fabric or the like by winding reinforcing fiber thread in a hoop shape, is formed in a barrel part A of the inner shell 2. On the other hand, the outer shell 3 is formed of CFRP by reinforcing resin by carbon fiber having tensile strength not less than 5500MPa. Therefore, weight is reduced, and excellent performance to falling impact is obtained, and it can be inexpensively manufactured.