A surgery supporting apparatus capable of performing a manipulation using a surgical instrument (21) to be inserted into a body cavity, comprises measurement means (22) arranged to measure an insertion depth and an insertion angle, with respect to the body cavity, of a shaft of the surgical instrument inserted into the body cavity, as input of the manipulation, wherein the measurement means is arranged to measure the insertion depth by measuring a sound wave propagating in a space between a transmitter (201) attached to one of the surgical instrument and a position within a predetermined range from a position of insertion to the body cavity, and a receiver (202) attached to the other.
