This pharmaceutical injection device comprises a main body case (2) having an injection needle extension/retraction opening (1) a pharmaceutical syringe mounting portion (3) provided inside the main body case (2) a piston (5) capable of moving relative to the pharmaceutical syringe mounting portion (3) a drive mechanism (6) for the piston (5) a controller (7) that is electrically connected to the drive mechanism (6) and an orientation sensor (8) that is electrically connected to the controller (7). The controller (7) controls the speed of the piston (5) in order to reduce liquid leakage during pharmaceutical mixing.
