The paper describes a calibrator for powermeters and calorimeters of high power and high energy lasers. It consists of a laser, an electronic circuit controlled electromagnetic shutter,a beam splitter, a laser calorimeter and a laser powermeter. The device can calibrate laser powermeters and calorimeters in the power range of 5-1000 W and energy range of 5-1000 J with a calibration accuracy of better than ±5%.