A communication device controls a process for determining a position of another device in accordance with a radio propagation environment. The communication device includes a wireless communication section configured to receive wireless signals from another communication device and a control section configured to calculate a reliability parameter. The reliability parameter serves as an indicator that indicates whether a first incoming wave serving as a signal detected as a signal that meets a predetermined detection standard is an appropriate process target, among the wireless signals received by the wireless communication section. The reliability parameter also controls a positional parameter determination process of determining a positional parameter indicating a position of the other communication device on a basis of the first incoming wave, and on a basis of the reliability parameter.