This disclosure provide a bottom sediment determining device, which is inputted with an echo signal corresponding to an ultrasonic wave outputted underwater, and determines water bottom sediment using a neural network. The device includes a memory for storing two or more parameters to be used in the neural network so as to be associated with positional information, a receiver for receiving the positional information, an acquisition module for acquiring the parameters corresponding to the positional information, and a setting module for setting the parameters to the neural network.