An electric motor control device includes: a motor constant generator configured to generate a motor constant by using a temperature; a current control unit configured to generate a current command value to an electric motor based on the motor constant and a torque command value and execute a current control mode; a voltage phase control unit configured to calculate a torque estimation value of the electric motor and execute a voltage phase control mode in which a feedback operation is performed for a voltage phase based on the difference between the torque estimation value and the torque command value; and a control mode switching unit configured to switch to the voltage phase control mode in a high rotation area where a flux weakening control is performed. The torque estimation value is calculated using the motor constant common to generation of the current command value in the current control mode.