The present specification relates to an automatic cleaner. The automatic cleaner, according to one aspect, comprises: a casing having an inlet port; a suction device which is installed inside the casing and sucks external foreign substances through the inlet port; a moving device for moving the casing; and a side brush assembly movably installed at the casing, wherein the side brush assembly comprises: a movable member which is provided so as to be movable in the casing and protrudes outside of the casing; a side brush provided so as to be rotatable at the movable member; a hinge shaft for enabling the rotation of the movable member; and an elastic member for supporting the hinge shaft or the movable member.