A co-rotating scroll compressor, comprising: a driving-side scroll member driven by a drive unit so as to rotate, and comprising a plurality of spiral driving-side walls (71b, 72b) provided about a center of a driving-side end plate (71a, 72a) at predetermined angular intervals; a driven-side scroll member comprising spiral driven-side walls (91b, 92b), the driven-side walls being provided about a center of a driven-side end plate at predetermined angular intervals and in a number corresponding to the driving-side walls (71b, 72b), the driven-side walls (91b, 92b) being engaged with the corresponding driving-side walls (71b, 72b) so as to form a compression space; a synchronous driving mechanism that transmits driving force from the driving-side scroll member to the driven-side scroll member so that the driving-side scroll member and the driven-side scroll member rotationally move in a same direction at a same angular velocity; and a housing comprising a motor accommodation part that accommodates a motor for rotating the driving-side scroll member, and a scroll accommodation portion that accommodates the scroll members (70, 90) and the synchronous driving mechanism, wherein the housing comprises: partition surfaces partitioned at a plane comprising the scroll members (70, 90) and orthogonal to rotational axes (CL1, CL2) of the scroll members; and fastening portions that fasten the partition surfaces in a region on a periphery of the scroll members and on a lateral side when seen from a straight line connecting the rotational axes of the scroll members to each other, characterized in that the fastening portions are provided on an inner side with respect to a circumscribed circle surrounding the driving-side scroll member and the driven-side scroll member, the circumscribed circle partially coming in contact with an external form of the scroll accommodation portion. a driving-side scroll member driven by a drive unit so as to rotate, and comprising a plurality of spiral driving-side walls (71b, 72b) provided about a center of a driving-side end plate (71a, 72a) at predetermined angular intervals; a driven-side scroll member comprising spiral driven-side walls (91b, 92b), the driven-side walls being provided about a center of a driven-side end plate at predetermined angular intervals and in a number corresponding to the driving-side walls (71b, 72b), the driven-side walls (91b, 92b) being engaged with the corresponding driving-side walls (71b, 72b) so as to form a compression space; a synchronous driving mechanism that transmits driving force from the driving-side scroll member to the driven-side scroll member so that the driving-side scroll member and the driven-side scroll member rotationally move in a same direction at a same angular velocity; and a housing comprising a motor accommodation part that accommodates a motor for rotating the driving-side scroll member, and a scroll accommodation portion that accommodates the scroll members (70, 90) and the synchronous driving mechanism, wherein the housing comprises: partition surfaces partitioned at a plane comprising the scroll members (70, 90) and orthogonal to rotational axes (CL1, CL2) of the scroll members; and fastening portions that fasten the partition surfaces in a region on a periphery of the scroll members and on a lateral side when seen from a straight line connecting the rotational axes of the scroll members to each other, partition surfaces partitioned at a plane comprising the scroll members (70, 90) and orthogonal to rotational axes (CL1, CL2) of the scroll members; and fastening portions that fasten the partition surfaces in a region on a periphery of the scroll members and on a lateral side when seen from a straight line connecting the rotational axes of the scroll members to each other, characterized in that the fastening portions are provided on an inner side with respect to a circumscribed circle surrounding the driving-side scroll member and the driven-side scroll member, the circumscribed circle partially coming in contact with an external form of the scroll accommodation portion.