To provide a selection assisting device of an automatic transmission capable of enlarging freedom in layout for the miniaturization of a selection lever while operating in failure by means of mechanical connection between the selection lever and a range position switching device and obtaining a selection lever operating force property in response to demands.

When switching operation to either of range positions is carried out and switching operation from the range position to an opposite direction is carried out, a compensation amount detecting and processing block 55, which calculates the amount of lost motions of control cables 8 and 18 and gaps on mechanically connected portions from detected positions of a potentiometer 51 and a potentiometer 25, is arranged.