Various examinations have been conducted on automatic hydraulic and electric motor-driven center stand systems for motorcycles. For practical application, problems, however, surfaced as to reconcile high output with small size including a backup mechanism to provide for possible failure in the system.Authors et al. have successfully developed a powerful, electric motor-driven power unit with a high-reduction gear transmission. Furthermore, by adopting high- efficiency worm gear for transmission, the unit was made both compact and lightweight. In addition, a backup mechanism was firmly established, that can be used even when the battery is discharged. As a result, it has become possible to install this automatic center stand system (auto-stand) in mass-production motorcycles.