To precisely measure steam leakage quantity and discharged condensate quantity of a bucket type steam trap.

A probe 1 in which a vibration detection means is built and a device main body 2 to process a detected vibration signal of the probe 1 are furnished, and the device main body 2 has a CUP 6 and a memory part 7. The memory part 7 memorizes the relation of a working cycle of a bucket type steam trap and steam leakage quantity and the relation of the working cycle and discharged condensate quantity. The working cycle and the steam leakage quantity have relation that the steam leakage quantity decreases as working hour increases and the steam leakage quantity decreases as the working cycle increases. The CPU 6 detects a working cycle of the bucket type steam trap from a supplied vibration signal and computes the steam leakage quantity and the discharged condensate quantity from the relation of this detected working cycle and the working cycle and the steam leakage quantity previously memorized in the memory part 7 and the steam leakage quantity and the relation of the working cycle and the discharged condensate quantity by detecting the working cycle of the bucket type steam trap from a supplied vibration signal.