Abstract: An automatic warming-up apparatus and a warming-up method applied in various hydraulic systems which are equipped with an engine and a hydraulic pump driven by the engine, and controlled by a microcomputer. The warming-up apparatus has at least one hydraulic actuator operated by an oil discharged from the hydraulic pump, a first temperature sensor detecting the temperature of a lubricant oil of the engine, a second temperature sensor detecting the temperature of a cooling water of the engine, a third temperature sensor detecting the temperature of a pressurized oil of the hydraulic system, an input/output unit sending to the controller the temperature signals received from the sensors.