A liquid level detector includes a casing having a first regulatory section and a second regulatory section, a float that has its upward and downward displacement restricted by contact with the first regulatory section or the second regulatory section, a magnet body that is held by the float, and a switch mechanism that is switched between an on-state and an off-state. A first distance from a switching plane to the first regulatory section and a second distance from the switching plane to the second regulatory section are both longer than a length from one magnet end face to a bottom end section.