A motor controller includes a command part that generates a command signal, a control part that drives a control object through an output filter when the command signal is input, an operating amount detector that detects an operating amount of the control object, a frequency response characteristic measurement part that generates an open loop frequency response characteristic on the basis of the command signal and the operating amount, a model calculation part that simulates a frequency characteristic of the output filter, and a display that displays the add result of an amplitude characteristic of the frequency characteristic of the frequency response characteristic measurement part and an amplitude characteristic of the frequency characteristic of the model calculation part.