Abstract: A heat generating part (1) of semiconductor manufacturing equipment is cooled by cooling water. An inner fluid passage (21) having an inlet port (31) of the cooling water on a vertically lower portion thereof is formed so as to surround a periphery of the heat generating part (1). An outer fluid passage (22) having an outlet port (32) of the cooling water on a vertically upper portion thereof is formed so as to surround a periphery of the inner fluid passage (21) and be capable of exchanging heat with the cooling water in the inner fluid passage. A communication passage (24) is provided to connect a vertically upper portion of said inner fluid passage and a vertically lower portion of said outer fluid passage. The cooling water flowing out of the outlet port (32) of the outer fluid passage (22) is supplied to the inlet port (31) of the inner fluid passage (21).