The invention discloses a gun in-place detection device. The gun in-place detection device comprises a supporting plate, a guide plate, a guide rod, a support plate, a hinge, a base plate, a support, an installing frame, a snap spring, a spring, a microswitch and screws, wherein the support plate is fixedly connected with the lower portion of the supporting plate, the supporting plate is connected with the base plate through the hinge, the guide plate is fixedly connected with the guide rod, the guide rod is sleeved with the spring, and is installed on the installing frame, the upper end, fixedly connected with the guide rod, of the guide plate is connected with the support plate, the snap spring is arranged at the lower end of the guide plate, one end of the support is connected with the base plate through the hinge, and the other end of the support is fixedly connected with the installing frame. The gun in-place detection device can be used for monitoring the in-place situation of a gun.