Method and apparatus for sensing liquid level of the invention includes a plurality of thermocouple elements that are formed by connecting two kind of thermocouple wires alternately in series into a plurality of thermometric contacts. The two kind of thermocouple wires have different thermoelectric powers SA and SB and have a variety of predetermined lengths. The invention can sense with high reliability a liquid level of a sensed liquid by changing electromotive forces from these thermocouple elements into binary signals by using fewer thermocouple elements than the conventional apparatus. The invention also includes thermocouple elements for parity check to self-diagnose the sensed result to inspect easily and securely errors in operation due to disconnections in the thermocouple elements or external noises.