There are provided a command speed calculation means (101) for outputting a command speed (ωr) from a base speed (ωb) and a ratio gain (α), reference speed generation means (108) calculating a reference speed (ωa) so as to follow the command speed (ωr) based on the command speed (ωr), control deviation calculation means (103) for outputting a control deviation (e) from a speed deviation (ωe) and a speed deviation correction value (ωec), speed control means (104) for outputting a compensation torque (τm) for decreasing the control deviation (e), speed deviation correction means (105) for calculating the speed deviation correction value (ωec) from at least the compensation torque (τm), command torque calculation means (107) for outputting a command torque (τr) from at least the compensation torque (τm) and ratio calculation means (102) for calculating the ratio gain (α) from the speed deviation (ωe).