Abstract: An inspection device and a method for detecting a firearm in a luggage are disclosed. The method comprises: performing X-ray inspection on the luggage to obtain a transmission image; determining a plurality of candidate regions in the transmission image using a trained firearm detection neural network; and classifying the plurality of candidate regions using the detection neural network to determine whether there is a firearm included in the transmission image. With the above solutions, it is possible to determine more accurately whether there is a firearm included in a luggage. In other embodiments, after a firearm is detected using the above method, a label is marked in the image to prompt an image judger.