A compressor, comprising: an attachment part protruded from an outer peripheral surface of a front housing and including a first end surface abutting on an attached member, a second surface opposed to the first end surface, a cylinder block, a crank chamber defined by the cylinder block and the housing, a piston and a bolt hole opened to both the first end surface and the second end surface; characterised in that a reinforcement part is integrally formed with the attachment part and the housing and extending from a side surface (211 b) of the attachment part formed along the bolt hole on the outer peripheral surface of the housing, wherein the reinforcement part includes a hollow portion that is formed by closing the first end surface side and opening the second end surface side and the reinforcement part includes: a bottom wall extending from the side surface of the attachment part to the outer peripheral surface of the housing in parallel to the first end surface of the attachment part; and a side wall (220b, 220c) standing from the bottom wall toward the second end surface of the attachment part and extending from the side surface of the attachment part to the outer peripheral surface of the front housing, and the bottom wall 220a protrudes outward in the radial direction of the front housing 102 in a direction orthogonal to the center line of the bolt hole 211a. an attachment part protruded from an outer peripheral surface of a front housing and including a first end surface abutting on an attached member, a second surface opposed to the first end surface, a cylinder block, a crank chamber defined by the cylinder block and the housing, a piston and a bolt hole opened to both the first end surface and the second end surface; characterised in that a reinforcement part is integrally formed with the attachment part and the housing and extending from a side surface (211 b) of the attachment part formed along the bolt hole on the outer peripheral surface of the housing, wherein the reinforcement part includes a hollow portion that is formed by closing the first end surface side and opening the second end surface side and the reinforcement part includes: a bottom wall extending from the side surface of the attachment part to the outer peripheral surface of the housing in parallel to the first end surface of the attachment part; and a side wall (220b, 220c) standing from the bottom wall toward the second end surface of the attachment part and extending from the side surface of the attachment part to the outer peripheral surface of the front housing, and the bottom wall 220a protrudes outward in the radial direction of the front housing 102 in a direction orthogonal to the center line of the bolt hole 211a. a bottom wall extending from the side surface of the attachment part to the outer peripheral surface of the housing in parallel to the first end surface of the attachment part; and a side wall (220b, 220c) standing from the bottom wall toward the second end surface of the attachment part and extending from the side surface of the attachment part to the outer peripheral surface of the front housing, and the bottom wall 220a protrudes outward in the radial direction of the front housing 102 in a direction orthogonal to the center line of the bolt hole 211a.