A pump unit 10 includes a micro pump 11 and an assist mechanism 12. The micro pump 11 includes: a housing 16 having an inflow port 11A and an outflow port 11B； and a pump device 32 built in the housing 16, the pump device transporting a fluid from the inflow port 11A to the outflow port 11B. The assist mechanism 12 includes a jet nozzle 12N for jetting a fluid. A jet port 12NA is opened at a tip portion 12NS of the jet nozzle 12N. The assist mechanism 12 is disposed in such a manner that a gap through which a fluid outside can flow is formed between the tip portion 12NS and the housing 16. The jet port 12NA is located in proximity to the inflow port 11A. The jet port 12NA directly faces the inflow port 11A.
