An in-vehicle computer generates a message authentication code about its own log using its own signature key and thereby transmits a log annotated with its message authentication code to a vehicle information collection device. The vehicle information collection device generates the signature key of the in-vehicle computer, verifies the message authentication code, which is included in the log annotated with its message authentication code received from the in-vehicle computer, using generated signature key, and thereby stores the log relating to the successfully verified message authentication code on storage media.