To correct the travelling direction of a self-propelled object so as to have a proper direction by utilizing the travelling force of the self-propelled object by a mechanical means even if the self-propelled object travels in a direction where it cannot normally enter into a charger when it enters the charger.

The charger has a seat plate portion 10, a power supply side terminal portion 30, a guiding portion 40 for correcting the travelling direction of the self-propelled object B, and a turning means 60 for turning the self-propelled object B before the guiding means 40 starts its operation. The turning means 60 consists of a rib longer than an opposite distance between right wheels 110 and left wheels 120 of the self-propelled object B. The rib as the turning means 60 is disposed on an inclined straddling surface 12 of the seat plate portion 10.