A simulation device , adapted for simulating a mechanical system which has a controlled object containing a motor and a motor control device controlling the motor , comprising: a frequency response function computing part , adapted for computing a frequency response function containing characteristics of the controlled object based on a relation between a first command value driving the mechanical system and a measured value of response of the mechanical system driven by the first command value; a simulation system , having a control block structure corresponding to the mechanical system ; a parameter setting part , adapted for setting the control parameter changing characteristics of the simulation system ; a frequency transfer function setting part , adapted for setting a frequency transfer function computed based on the frequency response function or based on the frequency response function and the control parameter into a frequency transfer function used for the simulation; a second command value generating part , adapted for generating a second command value which is a command value for simulation; a frequency response outputting part , adapted for outputting the frequency response characteristic of the mechanical system based on the frequency transfer function for simulation; characterized by a time response outputting part , adapted for executing time response simulation of the mechanical system relative to the second command value based on the second command value and the frequency transfer function for simulation; a display control part , adapted for displaying a result of the time response simulation and the frequency response characteristic on a display part simultaneously or selectively, and wherein the frequency response outputting part is adapted to output at least one of a gain response characteristic and a phase response characteristic as the frequency response characteristic. a frequency response function computing part , adapted for computing a frequency response function containing characteristics of the controlled object based on a relation between a first command value driving the mechanical system and a measured value of response of the mechanical system driven by the first command value; a simulation system , having a control block structure corresponding to the mechanical system ; a parameter setting part , adapted for setting the control parameter changing characteristics of the simulation system ; a frequency transfer function setting part , adapted for setting a frequency transfer function computed based on the frequency response function or based on the frequency response function and the control parameter into a frequency transfer function used for the simulation; a second command value generating part , adapted for generating a second command value which is a command value for simulation; a frequency response outputting part , adapted for outputting the frequency response characteristic of the mechanical system based on the frequency transfer function for simulation; characterized by a time response outputting part , adapted for executing time response simulation of the mechanical system relative to the second command value based on the second command value and the frequency transfer function for simulation; a display control part , adapted for displaying a result of the time response simulation and the frequency response characteristic on a display part simultaneously or selectively, and wherein the frequency response outputting part is adapted to output at least one of a gain response characteristic and a phase response characteristic as the frequency response characteristic. <EOS>