A pharmaceutical injection device may comprise a main body case having a cartridge holder, a piston that pushes out the pharmaceutical of a pharmaceutical cartridge held in the cartridge holder, a light emitting component, a light receiving component, and a controller. The light emitting component may shine light of different colors on the pharmaceutical cartridge disposed in the cartridge holder. The light receiving component receives light that has been shined from the light emitting component onto the pharmaceutical cartridge and reflected by the pharmaceutical cartridge. The controller may shine from the light emitting component and identify the type of pharmaceutical cartridge.