An electric motor control device that is configured to control driving of a plurality of electric motors (1, 2) connected in parallel with each other, the electric motor control device comprising: a power converter configured to convert power from a power supply, and supply the converted power to each of the plurality of electric motors (1, 2); a switching device configured to be turned on to electrically connect the power converter and at least one of the plurality of electric motors and configured to be turned off to electrically disconnect the power converter and the at least one of the plurality of electric motors; a current detection unit configured to detect a current that flows in the plurality of electric motors (1, 2); and a controller configured to control the power converter on a basis of operation of the switching device, rotation frequency command values from an external device, and a value of the current detected by the current detection unit, the controller being configured to perform control of turning the switching device from off to on in such a manner that start timing of control of decelerating the at least one of the plurality of electric motors is different from start timing of control of decelerating a remaining at least one of the plurality of electric motors, wherein the controller is configured to perform a process of deriving a rotation frequency estimation value of the remaining at least one of the plurality of electric motors on a basis of a phase and amplitude of an induced voltage in the remaining at least one of the plurality of electric motors obtained from the value of the current detected by the current detection unit, and, when the controller determines that a set time corresponding to the rotation frequency estimation value elapses after start of control of decelerating the remaining at least one of the plurality of electric motors at first, the controller is configured to turn the switching device from off to on or, wherein the controller is configured to turn the switching device from off to on when the controller determines that the value of the current detected by the current detection unit is not more than a set current after start of control of decelerating the remaining at least one of the plurality of electric motors at first. a power converter configured to convert power from a power supply, and supply the converted power to each of the plurality of electric motors (1, 2); a switching device configured to be turned on to electrically connect the power converter and at least one of the plurality of electric motors and configured to be turned off to electrically disconnect the power converter and the at least one of the plurality of electric motors; a current detection unit configured to detect a current that flows in the plurality of electric motors (1, 2); and a controller configured to control the power converter on a basis of operation of the switching device, rotation frequency command values from an external device, and a value of the current detected by the current detection unit, the controller being configured to perform control of turning the switching device from off to on in such a manner that start timing of control of decelerating the at least one of the plurality of electric motors is different from start timing of control of decelerating a remaining at least one of the plurality of electric motors, wherein the controller is configured to perform a process of deriving a rotation frequency estimation value of the remaining at least one of the plurality of electric motors on a basis of a phase and amplitude of an induced voltage in the remaining at least one of the plurality of electric motors obtained from the value of the current detected by the current detection unit, and, when the controller determines that a set time corresponding to the rotation frequency estimation value elapses after start of control of decelerating the remaining at least one of the plurality of electric motors at first, the controller is configured to turn the switching device from off to on or, wherein the controller is configured to turn the switching device from off to on when the controller determines that the value of the current detected by the current detection unit is not more than a set current after start of control of decelerating the remaining at least one of the plurality of electric motors at first.