The pharmaceutical injection device includes a pharmaceutical syringe mounting portion (3) provided within a main body case (2) and to which a pharmaceutical syringe (4) is removably mounted, a piston (5) provided movably with respect to the pharmaceutical syringe (4) mounted to the pharmaceutical syringe mounting portion (3), a drive mechanism (6) for driving the piston (5), a controller (7) that is electrically connected to the drive mechanism (6), a display section (35) that is connected to the controller (7), and an encoder (26) that is connected to the controller (7) and detects the amount of the pharmaceutical remaining inside the pharmaceutical syringe (4). The controller (7) displays a warning on the display section (35) recommending removal of the pharmaceutical syringe (4) from the pharmaceutical syringe mounting portion (3) when the presence of a pharmaceutical is detected by the encoder (26).