The present invention relates to an uninterruptible air supply system for aquarium which supplies air to an aquarium through an air supply device. The present invention includes: an AC electronic connector which respectively supplies electric power to the air supply device and a battery charging unit by being in contact in a direction of supplying external power if the external power is supplied and connects and supplies power to the air supply device by being in contact in a direction of supplying battery power in case of a power failure； a DC electronic connector which connects one side to the battery charging unit, connects an inverter with the AC electric connecter by connecting the other side with the inverter, charges battery by being in contact in the direction of the battery charging unit in case of supplying external power, and supplies the battery power to the air supply device which is connected to the AC electric connector by being in contact in the direction of the inverter in case of the power failure； and an air photo sensor having an installation body which forms an operation chamber and a flow path in which air passes by being connected to the air supply device, a rotation central axis which is installed in the operation chamber of the installation body, an opening and closing plate which opens and closes a flow path according to the supply of air by being combined with the rotation central axis and is processed by being coated with a mineral for a light reflection and also having a sensing unit which is composed of a substrate installed in the upper part of the operation chamber, a lamp which is installed in the lower part of one side of the substrate, and the sensor sensing light of the lamp through the opening and closing plate which is processed with a coating by being installed in the lower part of the other side of the substrate. The present invention recognizes the DC electric connector as a power failure since the sensor does not sense the l
