To easily achieve the operation without requiring much space by providing an adapter one end of which can be engaged with a handle engagement part on a jack side, and the other end of which can be engaged with a well-known tool such as a wrench and a hook.

This on-vehicle jacking device 20 comprises a jack body 1, an adapter 10A, and a ratchet wrench 5 on the market. In the jack body 1, a handle engagement part 2 is provided on one end of a shaft 1b screwed in a diamond link diagonally in the horizontal direction. A hole 2a in which a hook part 4a of an operation handle 4 is inserted, is opened in the handle engagement part 2. One end of the adapter 10A is engaged with the handle engagement part 2, and the other end is engaged with the ratchet wrench 5 on the market. The jack-up/jack-down operation can be easily achieved by operating the ratchet wrench 5, etc. Because the operation can be achieved immediately aside the vehicle body, an operator is safe even the operator is on the roadway side. In a narrow place such as a garage, it is convenient because no wide space is unnecessary.