A recording device incorporated in a vehicle, the recording device comprising: an imaging data acquisition unit configured (i) to acquire imaging data including video data and audio data, and (ii) to output the imaging data to a buffer memory; an event detection unit configured to detect occurrence of events; a speech analysis unit configured to determine whether or not the speech of a driver or a passenger of the vehicle is included in the audio data included in the imaging data acquired by the imaging data acquisition unit; and a recording control unit configured to record imaging data obtained from the buffer memory in a recording unit, wherein if an event is detected to have occurred in a preceding time period in which the imaging data is available to be obtained from the buffer memory, the recorded imaging data is first imaging data and includes the video data and the audio data for the time period, and if an event is not detected to have occurred in the preceding time period and speech of the driver or the passenger is included in the audio data, the recorded imaging data is second imaging data and includes the video data and not the audio data for the time period, and if an event is not detected to have occurred in the preceding time period and speech of the driver or the passenger is not included in the audio data, the recorded imaging data is first imaging data and includes the video data and the audio data for the time period, wherein the recording control unit is configured to record the first imaging data in the recording unit as overwrite-prohibited data, and record the second imaging data in the recording unit as overwritable data. an imaging data acquisition unit configured (i) to acquire imaging data including video data and audio data, and (ii) to output the imaging data to a buffer memory; an event detection unit configured to detect occurrence of events; a speech analysis unit configured to determine whether or not the speech of a driver or a passenger of the vehicle is included in the audio data included in the imaging data acquired by the imaging data acquisition unit; and a recording control unit configured to record imaging data obtained from the buffer memory in a recording unit, wherein if an event is detected to have occurred in a preceding time period in which the imaging data is available to be obtained from the buffer memory, the recorded imaging data is first imaging data and includes the video data and the audio data for the time period, and if an event is not detected to have occurred in the preceding time period and speech of the driver or the passenger is included in the audio data, the recorded imaging data is second imaging data and includes the video data and not the audio data for the time period, and if an event is not detected to have occurred in the preceding time period and speech of the driver or the passenger is not included in the audio data, the recorded imaging data is first imaging data and includes the video data and the audio data for the time period, wherein the recording control unit is configured to record the first imaging data in the recording unit as overwrite-prohibited data, and record the second imaging data in the recording unit as overwritable data.