A communication device includes: an acquisition unit that acquires first position information indicating a first position of the communication device and first position error information indicating an error of the first position; a reception unit that receives second position information indicating a second position of a communication device and second position error information indicating an error of the second position acquired by the communication device; a first calculation unit that calculates a first arrival direction and a first arrival direction error based on one or more pieces of information out of the first position information and so on; a second calculation unit that calculates a second arrival direction; and a judgment unit that makes the second calculation unit revise the second arrival direction based on the first arrival direction when the first arrival direction error is smaller than a first threshold value.