Leakage tester

An inexpensive and compact leakage tester is provided, which performs a leakage determination on a measurement object automatically and with high accuracy. The leakage tester of the present invention includes; a pressurizing device for pressurizing the inside of a measurement object; a pressurizing controlling section for controlling the pressurizing device so as to perform a first pressurizing operation and a second pressurizing operation; a pressure detecting section for detecting a pressure value in the measurement object at the stoppage of the first pressurizing operation and a pressure change value in the measurement object after the stoppage of the second pressurizing operation; a volume estimating section for estimating a volume of the measurement object based on at least the pressure value; and a leak determination section for determining a leak state of the measurement object based on pressure change information and the pressure change value.