An in-vehicle communication device configured to perform communication with a terminal device having key information of a vehicle, the in-vehicle communication device comprising: a transmission controller configured to perform control so that a first signal for activating the terminal device is transmitted from an outside-vehicle-cabin transmission antenna mounted outside the vehicle, and perform control so that a predetermined second signal is transmitted from the outside-vehicle-cabin transmission antenna and an inside-vehicle-cabin transmission antenna mounted inside the vehicle, after the transmission of the first signal; and a determination unit configured to determine whether the terminal device is present outside or inside the vehicle based on a first response signal that is transmitted from the terminal device to the in-vehicle communication device after the transmission of the second signal, wherein: the transmission controller is configured to perform, when the determination unit is unable to determine whether the terminal device is present outside or inside the vehicle, control so that a third signal for activating the terminal device is transmitted only from the inside-vehicle-cabin transmission antenna; and the determination unit is configured to determine whether the terminal device is present outside or inside the vehicle based on a second response signal that is transmitted from the terminal device to the in-vehicle communication device after the transmission of the third signal. a transmission controller configured to perform control so that a first signal for activating the terminal device is transmitted from an outside-vehicle-cabin transmission antenna mounted outside the vehicle, and perform control so that a predetermined second signal is transmitted from the outside-vehicle-cabin transmission antenna and an inside-vehicle-cabin transmission antenna mounted inside the vehicle, after the transmission of the first signal; and perform control so that a first signal for activating the terminal device is transmitted from an outside-vehicle-cabin transmission antenna mounted outside the vehicle, and perform control so that a predetermined second signal is transmitted from the outside-vehicle-cabin transmission antenna and an inside-vehicle-cabin transmission antenna mounted inside the vehicle, after the transmission of the first signal; and a determination unit configured to determine whether the terminal device is present outside or inside the vehicle based on a first response signal that is transmitted from the terminal device to the in-vehicle communication device after the transmission of the second signal, wherein: the transmission controller is configured to perform, when the determination unit is unable to determine whether the terminal device is present outside or inside the vehicle, control so that a third signal for activating the terminal device is transmitted only from the inside-vehicle-cabin transmission antenna; and the determination unit is configured to determine whether the terminal device is present outside or inside the vehicle based on a second response signal that is transmitted from the terminal device to the in-vehicle communication device after the transmission of the third signal. the transmission controller is configured to perform, when the determination unit is unable to determine whether the terminal device is present outside or inside the vehicle, control so that a third signal for activating the terminal device is transmitted only from the inside-vehicle-cabin transmission antenna; and the determination unit is configured to determine whether the terminal device is present outside or inside the vehicle based on a second response signal that is transmitted from the terminal device to the in-vehicle communication device after the transmission of the third signal.