A co-rotating scroll compressor comprising: a driving side scroll member (7, 70) rotatably driven by a drive part, having a plurality of spiral driving side wall bodies (7b, 71b, 72b) installed with a predetermined angular interval around a center of a driving side end plate (7a, 71a, 72a); a driven side scroll member (9, 90) installed with a predetermined angular interval around a center of a driven side end plate (9a, 90a), having a number of spiral driven side wall bodies (9b, 91b, 92b) corresponding to each of the driving side wall bodies (7b, 71b, 72b), and forming a compression space by engaging each of the driven side wall bodies (9b, 91b, 92b) with the corresponding driving side wall bodies (7b, 71b, 72b); a synchronous driving mechanism transmitting driving force from the driving side scroll member (7, 70) to the driven side scroll member (9, 90) so that the driving side scroll member (7, 70) and the driven side scroll member (9, 90) synchronously revolve; a first driving side bearing and a second driving side bearing (14, 26) rotatably supporting a shaft part (7c, 72c) of the driving side scroll member (7, 70) at one end side and the other end side in an axial direction; and a first driven side bearing (28, 37) and a second driven side bearing (13, 38) rotatably supporting a shaft part of the driven side scroll member (9, 90) at one end side and the other end side in the axial direction, wherein a preload is applied to the shaft part so that an axial clearance in a second driving side bearing direction is eliminated in the first driving side bearing, and a preload is applied to the shaft part so that an axial clearance in a first driving side bearing direction is eliminated in the second driving side bearing (14, 26), and/or a preload is applied to the shaft part so that an axial clearance in a second driven side bearing direction is eliminated in the first driven side bearing (28, 37), and a preload is applied to the shaft part so that an axial clearance in a first driven side bearing direction is eliminated in the second driven side bearing (13, 38). a driving side scroll member (7, 70) rotatably driven by a drive part, having a plurality of spiral driving side wall bodies (7b, 71b, 72b) installed with a predetermined angular interval around a center of a driving side end plate (7a, 71a, 72a); a driven side scroll member (9, 90) installed with a predetermined angular interval around a center of a driven side end plate (9a, 90a), having a number of spiral driven side wall bodies (9b, 91b, 92b) corresponding to each of the driving side wall bodies (7b, 71b, 72b), and forming a compression space by engaging each of the driven side wall bodies (9b, 91b, 92b) with the corresponding driving side wall bodies (7b, 71b, 72b); a synchronous driving mechanism transmitting driving force from the driving side scroll member (7, 70) to the driven side scroll member (9, 90) so that the driving side scroll member (7, 70) and the driven side scroll member (9, 90) synchronously revolve; a first driving side bearing and a second driving side bearing (14, 26) rotatably supporting a shaft part (7c, 72c) of the driving side scroll member (7, 70) at one end side and the other end side in an axial direction; and a first driven side bearing (28, 37) and a second driven side bearing (13, 38) rotatably supporting a shaft part of the driven side scroll member (9, 90) at one end side and the other end side in the axial direction, wherein a preload is applied to the shaft part so that an axial clearance in a second driving side bearing direction is eliminated in the first driving side bearing, and a preload is applied to the shaft part so that an axial clearance in a first driving side bearing direction is eliminated in the second driving side bearing (14, 26), and/or a preload is applied to the shaft part so that an axial clearance in a second driven side bearing direction is eliminated in the first driven side bearing (28, 37), and a preload is applied to the shaft part so that an axial clearance in a first driven side bearing direction is eliminated in the second driven side bearing (13, 38).