Abstract: A propeller shaft for transmitting driving force of a vehicle includes a first shaft unit mounted to the vehicle via a vehicle mounting member. The first shaft unit includes a sleeve yoke, a stub shaft, and a tube. The sleeve yoke is connected to an output shaft of a transmission of the vehicle, and receives the driving force via the output shaft. The stub shaft is disposed oppositely to the sleeve yoke in a direction of a rotational axis of the first shaft unit. The tube connects the sleeve yoke and the stub shaft. The stub shaft includes a weakest part structured to be less in torsional strength than a remaining part of the first shaft unit and formed at a position at which the stub shaft overlaps with the vehicle mounting member in the direction of the rotational axis.

Abstract: A storing unit stores traveling history information items on a vehicle, the traveling history information items being respectively associated with trips each being a segment from a start of a driving operation to an end of the driving operation. A determination unit determines whether to assign one of the traveling history information items, which is stored in the storing unit and associated with one trip, to a predetermined period, the one trip being partially included in the predetermined period. A driving operation diagnostic unit diagnoses a driving operation of a driver in the predetermined period according to the traveling history information item determined by the determination unit to be assigned to the predetermined period.

Abstract: A storing unit stores traveling history information items on a vehicle, the traveling history information items being respectively associated with trips each being a segment from a start of a driving operation to an end of the driving operation. A determination unit determines whether to assign one of the traveling history information items, which is stored in the storing unit and associated with one trip, to a predetermined period, the one trip being partially included in the predetermined period. A driving operation diagnostic unit diagnoses a driving operation of a driver in the predetermined period according to the traveling history information item determined by the determination unit to be assigned to the predetermined period.