Disclosed is a space-saving autonomous mobile robot capable of switching two types of light irradiation appropriately. The robot includes a moving mechanism, an autonomous movement controller for controlling the moving mechanism, a self-location recognition unit for sensing a self-location of the robot, a map data storage unit for storing a map data on locations of marks, a slit light device for irradiating a detection area with slit light, an infrared device for irradiating a detection area with infrared rays, and a switch determination unit for comparing a mark-formed region and the self-location, and then, for switching between the slit light and infrared devices, based on the comparison result. Moreover, the infrared device irradiates the detection area when the self-location is within the mark-formed region, while the slit light device irradiates the detection area when the self-location is outside the mark-formed region.