PURPOSE: To prevent skidding and other dangers for backward descending in a slope or the like by constructing a fluid-pressure holding valve to be provided only to hydrostatic systems for two wheels on a diagonal line.

CONSTITUTION: In a fluid-pressure holding valve 6, for braking on a sloping road or the like, a lever E interlocked with the operation of a clutch is rotated as an arrow shows so that a ball B may be seated on a valve seat C via an eccentric pin F and a rod D. In this construction, even if a brake pedal is released, the ball B is kept to be seated on the valve seat C to maintain the braked state as far as a clutch pedal is stepped on. The fluid-pressure holding valve 6 thus constructed is provided on a pipe (a) on one side near a master cylinder 3. This pipe (a) is connected for example to a front brake 4a on the left side and a rear brake 5b on the right side via a connector 7, pipes a1 and a2.