Provided is an air purifier in which the current position of a main body in the rotational direction can be ascertained. The air purifier is provided with the following: a main body that takes in air from the outside, purifies the air, and then blows the purified air to the outside; a support platform that is provided below the main body and that rotatably supports the main body; a barrier wall that is provided on one end of the main body and the support platform, protrudes towards the other end of the main body and the support platform, and has a plurality of slits that are arranged concentrically and concyclically; a plurality of sensors that are provided on the other end of the main body and the support platform, that are arranged concentrically and concyclically with the plurality of slits, and that perform detection on the slits that pass therethrough; and a control device that detects the current position of the main body in the rotational direction on the basis of the detection state of the slits by the plurality of sensors.