A pharmaceutical syringe unit (2, 2') that holds a pharmaceutical-filled pharmaceutical syringe and is mounted to a pharmaceutical injection device main body (100, 220) in order to mount the pharmaceutical syringe to a pharmaceutical injection device, the pharmaceutical syringe unit (2, 2') comprising: a distal end cap having openings on a front end side and a rear end side; and a syringe cover that is disposed on an inside of the distal end cap and that houses and holds the pharmaceutical syringe, characterized in that the distal end cap has: a guide component that guides a sliding of the syringe cover forward and backward with respect to the distal end cap; wherein said guide component has a guide groove into which a guided part that is provided to an outer peripheral part of the syringe cover fits, and stoppers (60a, 60b) that prevent the guided part from coming out of the guide groove; and a first engagement component that can be engaged with the pharmaceutical injection device main body (100, 220), wherein the syringe cover has: a needle mounting component on a front end portion that is used to mount an injection needle for injecting the pharmaceutical, and wherein the syringe cover is able to move between a needle insertion position at which operation of inserting the injection needle into a skin is completed, and a needle withdrawal position at which operation of withdrawing the injection needle from the skin is completed when the pharmaceutical syringe unit (2, 2') is mounted to a pharmaceutical injection device main body (100, 220), and a distance which the syringe cover can be slid forward and backward between the stoppers (60a, 60b) by the guide component is greater than distance between the needle insertion position and the needle withdrawal position. a distal end cap having openings on a front end side and a rear end side; and a syringe cover that is disposed on an inside of the distal end cap and that houses and holds the pharmaceutical syringe, a guide component that guides a sliding of the syringe cover forward and backward with respect to the distal end cap; wherein said guide component has a guide groove into which a guided part that is provided to an outer peripheral part of the syringe cover fits, and stoppers (60a, 60b) that prevent the guided part from coming out of the guide groove; and a first engagement component that can be engaged with the pharmaceutical injection device main body (100, 220), a needle mounting component on a front end portion that is used to mount an injection needle for injecting the pharmaceutical, and wherein the syringe cover is able to move between a needle insertion position at which operation of inserting the injection needle into a skin is completed, and a needle withdrawal position at which operation of withdrawing the injection needle from the skin is completed when the pharmaceutical syringe unit (2, 2') is mounted to a pharmaceutical injection device main body (100, 220), and a distance which the syringe cover can be slid forward and backward between the stoppers (60a, 60b) by the guide component is greater than distance between the needle insertion position and the needle withdrawal position.