Abstract: An annular fitting recess is formed circumferentially in the exterior of a tank body in the vicinity of the boundary between a dome section and a cylindrical gas discharge section of the tank body. A cylindrical reinforcing collar is fitted onto the cylindrical gas discharge section of the tank body to fit an annular boss of the reinforcing collar in the fitting recess of the tank body and then engaged integrally on the exterior of the tank body between the cylindrical gas discharge section and the dome section by shrinkage. This provides easily and inexpensively a high-pressure tank capable of withstanding high pressures of 35 to 75 MPa while keeping its lightness in weight.