To avoid an accidental start of a parking action, which starts unexpectedly for a vehicle driver, by displaying or performing a control action only when an action signal inputted by a user for starting a parking action is inputted.

It is checked whether an action signal for starting a parking space investigation is inputted or not, or a parking space is measured (101, 102). The dimension of the space is checked on the basis of this measurement (103), and if it is determined that the dimension is sufficient, this result is displayed (104). Subsequently, it is checked whether an action signal is inputted or not (105). If input of the action signal is checked, a parking operation is started, and a target curve for traveling the vehicle during its entrance into the parking space is found, and then, the vehicle is driven (107). In this predetermined duration, it is checked whether a brake of the vehicle is operated or not, and if the brake is operated, the parking action is stopped (108).