HYBRID WORK MACHINE

Provided is a hybrid work machine capable of performing a warm-up operation on an electric storage device by charging and discharging while suppressing the occurrence of lug-down or over-revolution to an engine. The hybrid work machine includes: an engine; an assist motor mechanically connected to the engine, causing a discharge by generating a drive torque, and generating electric power by generating a brake torque; a hydraulic pump driven by a total torque of the engine and the assist motor; an electric storage device storing the electric power generated by the assist motor and supplying the electric power when the assist motor is discharged; and a controller outputting a torque command signal in order to control the drive torque or the brake torque of the assist motor. The hybrid work machine further includes a torque-command-value arithmetic unit calculating a hydraulic pump torque necessary to drive the hydraulic pump, and calculating the torque command signal that is equal to or lower than a value obtained by subtracting a preset minimum torque of the engine from the hydraulic pump torque.