To provide a portable gravity meter containing memory for storing the changes of gravity data, temperature and atmospheric pressure inside the gravity meter and power source voltage in the memory and a gravity measuring method capable of obtaining gravity value without relying on others' judgment.

An analog/digital converter 10 converting analog signal corresponding to gravity change to digital value, a memory 20 storing the gravity data of the analog/digital converter 10, a signal level comparator circuit 30 detecting the stabilization of the measured gravity data, a data transmission means 40 reading the gravity data in the memory into external components, and a battery for power source 50 are installed in one together with a constant temperature tank containing weights and springs. The stabilization of the gravity data is checked and a series of measurement is conducted. Based on the measured gravity data and other data, drift and jump included in the gravity data are automatically corrected.