A communication apparatus includes: a setting unit that sets plural candidate points which are candidates of positions of a transmitter based on a position of one of plural receivers that receive radio waves from the transmitter; and a specifying unit that specifies a position of the transmitter from among the plural candidate points by using (i) strengths of the radio waves which one or more receivers including a receiver other than the one receiver receive from the transmitter and (ii) strengths of the radio waves which are inferred to be received by the one or more receivers from the transmitter when it is assumed that the transmitter exists at each of the plural candidate points.