The medical device tightness detector is suitable for the determination of the tightness and rupture strength of various materials such as medical devices, sterile packaging bags, infusion sets, catheters, composite hoses, composite cylinders, etc. A certain positive pressure gas is injected into the sample through the special tool of the sealing tester, and after a certain pressure holding time, the instrument automatically judges whether the sample is sealed well or the pressure value at the time of blasting.