A control method for a hybrid vehicle including an engine and an electric generator that generates electric power using power from the engine connected to the electric generator via a gear, the control method comprising: a rotation speed control torque calculation step of, based on a rotation speed command value for the electric generator and a rotation speed detection value of the electric generator, calculating a torque command value for controlling a rotation speed of the electric generator; and an electric generator control step of controlling the electric generator according to the torque command value, wherein the rotation speed control torque calculation step calculates, using a model matching compensator and based on a value related to the speed detection value and the rotation speed command value, a basic torque command value that makes a torque response of the electric generator coincide with a preset model response; calculates, using a disturbance observer including a transfer function composed of an inverse system of a control object model patterned after a power transmission system of the electric generator connected to the engine via the gear and a disturbance observer filter composed of a low-pass filter, and based on the rotation speed detection value, a disturbance torque that is input into the power transmission system; and calculates the torque command value based on the basic torque command value and the disturbance torque, and characterized in that a relative degree of the disturbance observer filter is set so that a relative degree of the transfer function becomes 1 or more, and the value related to the speed detection value is obtained by filtering the rotation speed detection value through a low-pass filter. a rotation speed control torque calculation step of, based on a rotation speed command value for the electric generator and a rotation speed detection value of the electric generator, calculating a torque command value for controlling a rotation speed of the electric generator; and an electric generator control step of controlling the electric generator according to the torque command value, wherein the rotation speed control torque calculation step calculates, using a model matching compensator and based on a value related to the speed detection value and the rotation speed command value, a basic torque command value that makes a torque response of the electric generator coincide with a preset model response; calculates, using a disturbance observer including a transfer function composed of an inverse system of a control object model patterned after a power transmission system of the electric generator connected to the engine via the gear and a disturbance observer filter composed of a low-pass filter, and based on the rotation speed detection value, a disturbance torque that is input into the power transmission system; and calculates the torque command value based on the basic torque command value and the disturbance torque, and characterized in that a relative degree of the disturbance observer filter is set so that a relative degree of the transfer function becomes 1 or more, and the value related to the speed detection value is obtained by filtering the rotation speed detection value through a low-pass filter.