Abstract: It is sought to provide a small-size and highly safe bellows pump dealing with an explosive gas or the like as pump feed fluid, which can prevent hazards due to reaching of a drive motor or like drive part by the pump feed fluid caused to leak out when the bellows is broken. A flexible partition membrane is stretched between the movable end of the bellows and the pump housing to make the outside-bellows region to be a sealed chamber. The flexible partition membrane can follow the reciprocation of the bellows and does not interfere with the operation thereof. When the pump feed fluid leaks out from the pump chamber due to breakage of the bellows during operation thereof, it is retained in the sealed outside-bellows region, and does not reach the drive part including the drive motor. Also, the flexible partition membrane prevents dust intrusion to the bellows side, thus preventing such troubles as the breakage of the bellows otherwise stemming from the dust intrusion.