PURPOSE: To accomplish invariably accurate indication of amount of fuel left by enabling the calculation thereof at the detection of the level through memorization of the liquid level in the fuel tank of the vehicle corresponding to the actual volume by stages.

CONSTITUTION: RAM 11g in a microcomputer 11 is provided to memorize the relationship between the amount of fuel supplied into the fuel tank and corresponding level of the fuel by stages up to the full capacity beforehand. The level of the fuel in the tank is detected with a sender 5 and an A/C converter 6 following up the running of the vehicle and the detection data is fed to the computer 11. The computer 11 searches liquid levels in the RAM 11g based on the date to obtain a proper indication data and drives an indicator to produce a digital indication of the amount of fuel left. In this manner, it is possible to accomplish invariably accurate indication of amount of fuel left regardless of the shape of tanks.