To simplify the system configuration by embodying on the electric command system and secure sufficient safety in the on-slope start assisting function.

A car stop sensing means S1 (S1a-S1d) senses a car stopping and emits a stop sensing signal, and a computational processing means 1 emits a command signal for brake pressure in compliance with the electric signal to a brake pressure generating means 2 (2a-2d) until the car stops, subjects the fed electric signals to a computational processing when the means S1 senses that the car has stopped, generates a brake pressure higher than the brake pressure when the car is stopped, and gives this brake pressure to the brake pressure generating means 2 as a hold command pressure.