A caliper for an opposed-piston type disc brake, comprising: an inner body which is disposed on an axially inner side of a rotor and includes two or more inner cylinder portions (14a, 14b) on a radially outer side and two or more inner cylinder portions (15a, 15b) on a radially inner side in two stages in a radial direction; an outer body which is disposed on an axially outer side of the rotor and includes two or more outer cylinder portions (18a, 18b) on the radially outer side and two or more outer cylinder portions (19a, 19b) on the radially inner side in two stages in the radial direction; a rotation-in side connecting portion and a rotation-out side connecting portion which are disposed radially outward than an outer circumferential edge of the rotor, and connect both circumferential end potions of the inner body and both circumferential end portions of the outer body; and two or more center bridges (6a, 6b) which are disposed between the rotation-in side connecting portion and the rotation-out side connecting portion in a circumferential direction and radially outward than the outer circumferential edge of the rotor, and connect a circumferentially intermediate portion of the inner body and a circumferentially intermediate portion of the outer body, wherein a belt-shaped rib extending in the circumferential direction is provided at least on an axially outer side surface of the outer body, and the belt-shaped rib covers radially inner side portions of bottom portions of the outer cylinder portions (18a, 18b) on the radially outer side and radially outer side portions of bottom portions of the outer cylinder portions (19a, 19b) on the radially inner side from an axially outer side so as to traverse the same in the circumferential direction, and wherein axially outer end portions of the center bridges (6a, 6b) are connected to the outer cylinder portions (18a, 18b) on the radially outer side, and the center bridges (6a, 6b) which are adjacent to each other in the circumferential direction are connected to each other by connecting portions (30a, 30b) located on a side farther from the rotor in an axial direction of the rotor than tip end portions of pistons (16a, 16b, 17a, 17b, 18a, 18b, 19a, 19b) incorporated in cylinder portions (14a, 14b, 15a, 15b, 18a, 18b, 19a, 19b) on the radially outer side and the radially inner side which are provided in at least one of the inner body and the outer body. an inner body which is disposed on an axially inner side of a rotor and includes two or more inner cylinder portions (14a, 14b) on a radially outer side and two or more inner cylinder portions (15a, 15b) on a radially inner side in two stages in a radial direction; an outer body which is disposed on an axially outer side of the rotor and includes two or more outer cylinder portions (18a, 18b) on the radially outer side and two or more outer cylinder portions (19a, 19b) on the radially inner side in two stages in the radial direction; a rotation-in side connecting portion and a rotation-out side connecting portion which are disposed radially outward than an outer circumferential edge of the rotor, and connect both circumferential end potions of the inner body and both circumferential end portions of the outer body; and two or more center bridges (6a, 6b) which are disposed between the rotation-in side connecting portion and the rotation-out side connecting portion in a circumferential direction and radially outward than the outer circumferential edge of the rotor, and connect a circumferentially intermediate portion of the inner body and a circumferentially intermediate portion of the outer body, wherein a belt-shaped rib extending in the circumferential direction is provided at least on an axially outer side surface of the outer body, and the belt-shaped rib covers radially inner side portions of bottom portions of the outer cylinder portions (18a, 18b) on the radially outer side and radially outer side portions of bottom portions of the outer cylinder portions (19a, 19b) on the radially inner side from an axially outer side so as to traverse the same in the circumferential direction, and wherein axially outer end portions of the center bridges (6a, 6b) are connected to the outer cylinder portions (18a, 18b) on the radially outer side, and the center bridges (6a, 6b) which are adjacent to each other in the circumferential direction are connected to each other by connecting portions (30a, 30b) located on a side farther from the rotor in an axial direction of the rotor than tip end portions of pistons (16a, 16b, 17a, 17b, 18a, 18b, 19a, 19b) incorporated in cylinder portions (14a, 14b, 15a, 15b, 18a, 18b, 19a, 19b) on the radially outer side and the radially inner side which are provided in at least one of the inner body and the outer body.