A cylindrical case made of a composite material of reinforcing fibers impregnated with a thermosetting resin, the cylindrical case including: a case main body which forms a cylindrical shape; and an outward flange which is disposed on an outer peripheral surface of the case main body annularly along a circumferential direction, wherein the outward flange includes: a bonding layer bonded on the outer peripheral surface of the case main body; a foundation layer having a triangular shape in cross-section and disposed on the bonding layer in the circumferential direction of the case main body; one flange constituting layer integrally having a leg layer which is laminated from one slope surface of the foundation layer to the bonding layer on the side of the one slope surface, and a wall layer which rises from the one slope surface of the foundation layer in a distal direction; and the other flange constituting layer integrally having a leg layer which continues to the bonding layer and is laminated from the other slope surface of the foundation layer to the bonding layer on the side of the other slope surface, and a wall layer which rises from the other slope surface of the foundation layer in the distal direction and overlaps with the wall layer of the one flange constituting layer, the foundation layer is formed by laminating roving layers including a roving composed of a bundle of reinforcing fibers, and the one flange constituting layer integrally having the leg layer and the wall layer and the other flange constituting layer integrally having the bonding layer, the leg layer, and the wall layer are both formed by laminating a plurality of biaxial fabric layers including a biaxial fabric of a non-crimp structure composed of two axes of reinforcing fiber bands (15a, 15b) having an orientation angle of ±15-75° to an axial direction of the case main body. a case main body which forms a cylindrical shape; and an outward flange which is disposed on an outer peripheral surface of the case main body annularly along a circumferential direction, wherein the outward flange includes: a bonding layer bonded on the outer peripheral surface of the case main body; a foundation layer having a triangular shape in cross-section and disposed on the bonding layer in the circumferential direction of the case main body; one flange constituting layer integrally having a leg layer which is laminated from one slope surface of the foundation layer to the bonding layer on the side of the one slope surface, and a wall layer which rises from the one slope surface of the foundation layer in a distal direction; and the other flange constituting layer integrally having a leg layer which continues to the bonding layer and is laminated from the other slope surface of the foundation layer to the bonding layer on the side of the other slope surface, and a wall layer which rises from the other slope surface of the foundation layer in the distal direction and overlaps with the wall layer of the one flange constituting layer, the foundation layer is formed by laminating roving layers including a roving composed of a bundle of reinforcing fibers, and the one flange constituting layer integrally having the leg layer and the wall layer and the other flange constituting layer integrally having the bonding layer, the leg layer, and the wall layer are both formed by laminating a plurality of biaxial fabric layers including a biaxial fabric of a non-crimp structure composed of two axes of reinforcing fiber bands (15a, 15b) having an orientation angle of ±15-75° to an axial direction of the case main body. a bonding layer bonded on the outer peripheral surface of the case main body; a foundation layer having a triangular shape in cross-section and disposed on the bonding layer in the circumferential direction of the case main body; one flange constituting layer integrally having a leg layer which is laminated from one slope surface of the foundation layer to the bonding layer on the side of the one slope surface, and a wall layer which rises from the one slope surface of the foundation layer in a distal direction; and the other flange constituting layer integrally having a leg layer which continues to the bonding layer and is laminated from the other slope surface of the foundation layer to the bonding layer on the side of the other slope surface, and a wall layer which rises from the other slope surface of the foundation layer in the distal direction and overlaps with the wall layer of the one flange constituting layer, the foundation layer is formed by laminating roving layers including a roving composed of a bundle of reinforcing fibers, and the one flange constituting layer integrally having the leg layer and the wall layer and the other flange constituting layer integrally having the bonding layer, the leg layer, and the wall layer are both formed by laminating a plurality of biaxial fabric layers including a biaxial fabric of a non-crimp structure composed of two axes of reinforcing fiber bands (15a, 15b) having an orientation angle of ±15-75° to an axial direction of the case main body.