Liquid level detecting device

A device comprising:

• a sensor housing having a circular rotation recess;
• a circular holder which is fitted in the rotation recess and is held rotatably by the sensor housing;
• a float arm which is fixed to the holder;
• a float which is attached to a tip portion of the float arm and varies in position following a liquid surface of liquid stored in a tank;
• a magnet having a circular-ring shape and which is provided in the holder;
• and
• a Hall element which is provided in the sensor housing and detects a displacement of the magnet,
• wherein the sensor housing has a lock groove which is formed over an inner circumference portion of the rotation recess in a circumference direction of the circular rotation recess and a pair of insertion holes which are formed at opposite positions on a circumferential edge of the rotation recess so as to communicate with the lock groove;
• wherein the holder has a pair of flanges which project in opposite directions from an outer circumferential surface of the holder and are engaged with the lock groove and prevented from coming off the rotation recess by setting the flanges opposed to the respective insertion holes, fitting the flanges into the rotation recess, and then rotating the flanges;
• and
• wherein the holder has a pair of support projections which come into contact with a bottom surface of the rotation recess and the pair of support projections are arranged at middle positions between the flanges respectively in a circumferential direction of the holder.