Disclosed are a mobile robot and a mobile robot charge station return system, the mobile robot having a simplified structure by commonly using a detection sensor capable of both receiving charge station guide signals and obstacle detection signals, the two types of signals having different frequencies. The mobile robot includes a signal reception unit including one or more detection sensors for both receiving obstacle detection signals of different frequency bands and the charge station position guide signals outputted from a charge station; and a controller for separating and detecting the obstacle detection signals and the charge station position guide signals, which are outputted from the signal reception unit, according to frequency bands, and controlling an operation of the mobile robot according to the detected signals.