A mobile robot apparatus includes a main body, a first wheel on a first side surface of the main body, a second wheel on a second side surface of the main body, where the first wheel and the second wheel include side surfaces having a convex shape, a first driving device configured to rotate the first wheel and the second wheel, a second driving device configured to move the first wheel and the second wheel to a first position or a second position, and a processor configured to, based on determining that the mobile robot apparatus is inverted to one side, control the second driving device to move a ground-engaging wheel from among the first wheel and the second wheel from the second position to the first position.