A recording/reproduction system comprising an in-vehicle recording/ reproduction device and a recording/reproduction device which receive the same signal and can communicate with each other, wherein the in-vehicle recording/reproduction device is provided in a vehicle, the recording/reproduction device is provided outside the vehicle, the in-vehicle recording/reproduction device comprises: a first recording device into which data can be recorded and from which the recorded data can be read out; a reproducing means of reading and reproducing the data recorded in the first recording device; a recording information transmitting means of, when starting recording the data in the in-vehicle recording/reproduction device, transmit-ting to the recording/reproduction device recording information about the data which the in-vehicle recording/reproduction device started recording; a reproduction information transmitting means of transmitting to the recording/reproduction device reproduction information indicating a time point where reproduction was stopped; and a data transmitting means of, after the recording information is transmitted, transmitting to the recording/reproduction device data which is recorded for a predetermined time from start of recording, where said predetermined time is determined based on a time lag caused by the communication between said in-vehicle recording/reproduction device and said other recording/reproduction device, the recording/reproduction device comprises: a second recording device of recording the same data as the data recorded in the in-vehicle recording/reproduction device based on the recording information transmitted from the in-vehicle recording/reproduction device; a reproduction starting means of starting reproduction from the position where reproduction was stopped in the in-vehicle recording/ reproduction device based on the reproduction information from the in-vehicle recording/reproduction device; and a data receiving/recording means of recording the data transmitted from the data transmitting means so that the data is continuously linked to the data which has already been recorded in the recording/reproduction device based on said recording information transmitted from the in-vehicle recording/ reproduction device. a first recording device into which data can be recorded and from which the recorded data can be read out; a reproducing means of reading and reproducing the data recorded in the first recording device; a recording information transmitting means of, when starting recording the data in the in-vehicle recording/reproduction device, transmit-ting to the recording/reproduction device recording information about the data which the in-vehicle recording/reproduction device started recording; a reproduction information transmitting means of transmitting to the recording/reproduction device reproduction information indicating a time point where reproduction was stopped; and a data transmitting means of, after the recording information is transmitted, transmitting to the recording/reproduction device data which is recorded for a predetermined time from start of recording, where said predetermined time is determined based on a time lag caused by the communication between said in-vehicle recording/reproduction device and said other recording/reproduction device, a second recording device of recording the same data as the data recorded in the in-vehicle recording/reproduction device based on the recording information transmitted from the in-vehicle recording/reproduction device; a reproduction starting means of starting reproduction from the position where reproduction was stopped in the in-vehicle recording/ reproduction device based on the reproduction information from the in-vehicle recording/reproduction device; and a data receiving/recording means of recording the data transmitted from the data transmitting means so that the data is continuously linked to the data which has already been recorded in the recording/reproduction device based on said recording information transmitted from the in-vehicle recording/ reproduction device.