A compression molding system comprising: a compression molding machine including a table having a vertically penetrating die bore, a filling device including an agitating rotor, facing the die bore of the table and configured to be displaced relatively to the table and fill, with a powdery material, the die bore passing vertically below the filling device, and an upper punch and a lower punch configured to compress the powdery material filled in the die bore to obtain a molded product; a powdery material feeding device configured to feed, with a powdery material, the filling device in the molding machine in operation; and a controller, wherein the controller is configured, upon start of the molding machine having stopped relative displacement of the filling device to the table and having stopped compression of the powdery material by the upper punch and the lower punch, to preliminarily supply the filling device with a predetermined amount of a powdery material from the powdery material feeding device while relative displacement of the filling device and compression by the upper punch and the lower punch is stopped, and to subsequently start the molding machine to cause relative displacement of the filling device and compression by the upper punch and the lower punch, characterized in that the controller is configured to cause the filling device to keep rotation of the agitating rotor while the molding machine is stopped, wherein the agitating rotor has a rotational speed lower than the rotational speed for sequentially filling, with the powdery materials, the die bores of the rotating table in the molding machine in operation, or wherein the agitating rotor is rotated only by a rotation angle or a number of times smaller than the rotation angle or the number of times for the molding machine in operation. a compression molding machine including a table having a vertically penetrating die bore, a filling device including an agitating rotor, facing the die bore of the table and configured to be displaced relatively to the table and fill, with a powdery material, the die bore passing vertically below the filling device, and an upper punch and a lower punch configured to compress the powdery material filled in the die bore to obtain a molded product; a powdery material feeding device configured to feed, with a powdery material, the filling device in the molding machine in operation; and a controller, wherein the controller is configured, upon start of the molding machine having stopped relative displacement of the filling device to the table and having stopped compression of the powdery material by the upper punch and the lower punch, to preliminarily supply the filling device with a predetermined amount of a powdery material from the powdery material feeding device while relative displacement of the filling device and compression by the upper punch and the lower punch is stopped, and to subsequently start the molding machine to cause relative displacement of the filling device and compression by the upper punch and the lower punch, to preliminarily supply the filling device with a predetermined amount of a powdery material from the powdery material feeding device while relative displacement of the filling device and compression by the upper punch and the lower punch is stopped, and to subsequently start the molding machine to cause relative displacement of the filling device and compression by the upper punch and the lower punch, characterized in that the controller is configured to cause the filling device to keep rotation of the agitating rotor while the molding machine is stopped, wherein the agitating rotor has a rotational speed lower than the rotational speed for sequentially filling, with the powdery materials, the die bores of the rotating table in the molding machine in operation, or wherein the agitating rotor is rotated only by a rotation angle or a number of times smaller than the rotation angle or the number of times for the molding machine in operation.