To provide an injection molding machine constituted so as to miniaturize a mold as a whole to reduce the processing cost of the mold and capable of being miniaturized itself.

The injection molding machine is equipped with a plurality of tie bars 1 parellelly extending toward an injection nozzle from a mold driving device, the movable platen 3 supported by the tie bars 1 to be moved by the mold driving device and the fixed platen 2 supported on the terminal ends on the side of the injection nozzle of the tire bars 1 and constituted so as to allow the movable platen 3 to advance and retreat to perform the mold clamping/opening of a mold. Since a conventional exclusive mold base is made unnecessary by providing recessed parts to the opposed surfaces of both platens 2 and 3 and immediately mounting cassette molds 4 and 5 in the recessed parts, the mold is miniaturized as a whole not only to reduce the processing cost of the mold but also to miniaturize the molding machine itself.