The present invention relates to a photoelectric smoke detector having a double-bulkhead darkroom structure and, more particularly, to a photoelectric smoke detector having a double-bulkhead darkroom structure, comprising: a base having, on one side thereof, a light emitting element receiving part in which a light emitting element for irradiating light to the inside thereof is mounted and, on the other side thereof, a light receiving element part in which a light element for receiving scattered light generated by smoke particles from the light irradiated by the light emitting element is mounted; an outer bulkhead which protrudes toward a lower side of the base to form an outer wall of the smoke detector and in which a smoke inlet having a specific height is formed in a circumferential direction; a lower end surface coupled to a lower end of the outer bulkhead; and an inner bulkhead which protrudes from the lower end surface to an upper side, is disposed to be spaced apart from the outer bulkhead at a specific interval, and is formed to have a height smaller than the height of the outer bulkhead so as to form a gas flow area in an upper portion thereof, wherein smoke flows in through the smoke inlet and passes through a space between the outer bulkhead and the inner bulkhead, and the gas flow area.