A water leakage detection system for a laser device detects a water leakage in the laser device including: a part group for outputting laser light; a water cooling plate which cools at least a portion of the part group; an enclosed housing in which the part group and the water cooling plate are stored; and an air circulating unit which circulates air within the housing, the air circulating unit is provided in the vicinity of a part having high heat generation and the water leakage detection system for the laser device includes: a humidity detection unit which detects humidity within the housing; temperature detection units which are arranged in a plurality of places in the water cooling plate and which respectively detect the temperatures of the places; and a detection control unit which outputs detection information when the humidity acquired from the humidity detection unit exceeds reference humidity or when at least one of the temperatures acquired from the temperature detection units exceeds a reference temperature of the corresponding place.