Intended is to provide a molding machine using a built-in type motor as an injecting electric motor. In this molding machine, a mounting structure for such a transmission mechanism from a rotational motion to a linear motion, as changes the rotation of the built-in motor into the linear motion thereby to transmit the linear motion to an injecting member, is simplified to improve the assembling workability. For this improvement, a sleeve is fixed in the rotor of the built-in type motor. In the hollow portion of the sleeve, a screw shaft or the rotating portion of a ball screw mechanism and the sleeve are connected and fixed by a connecting member. A nut member or the straight portion of the ball screw mechanism is fixed on a member for performing straight motions together with the injecting member.