HITCH ANGLE DETECTION SYSTEM, HITCH ANGLE DETECTION DEVICE, AND NON-TRANSITORY RECORDING MEDIUM

A hitch angle detection device detects a trailer hitch angle based on a trailer image shot by a vehicle camera using a model obtained by performing learning using learning data of a learning trailer image shot by a learning vehicle camera and a label indicating learning trailer hitch angle, additional learning of the model is performed in a server by using additional learning data of an additional learning trailer image shot by the vehicle camera and the label indicating the trailer hitch angle when the additional learning trailer image is shot, input of the trailer hitch angle is accepted by a vehicle HMI, the hitch angle detection device detects the trailer hitch angle based on the trailer image shot by the vehicle camera by using the model with the additional learning performed in the server.