A motor selection device includes a computer including a storage device and a calculation device. The storage device stores data of acceleration time, constant speed time, deceleration time, stop time, maximum output torque for each motor, dynamic friction torque, and constant load torque. To select selectable motors and to suggest an optimal operation pattern among motor operation patterns, the calculation device includes a central processing unit (CPU) and performs effective torque calculation by calculating torque in the acceleration time, in the constant speed time, in the deceleration time, and in the stop time based on data stored in the storing unit, and calculating the effective torque by giving a first torque, a second torque, a third torque, a fourth torque, the acceleration time, the constant speed time, the deceleration time, and the stop time to a predetermined formula.