To provide a base vehicle and a work vehicle which properly sets a relief pressure according to replacement of a work unit.

The base vehicle 10 detachably mounted with various work units, includes pipe joints 74, 74' detachably connecting a discharging conduit 73 of a hydraulic pump 72 to a hydraulic circuit of the work unit, a proportion electromagnetic relief valve 88 provided in a conduit 77 branching off from the discharging conduit 73 and communicating to a tank 76, an electric connector 93 connecting an electric system to the work unit, and a control device 90 giving an instruction to the proportion electromagnetic relief valve 88 on the basis of the classification information of the work units obtained through the electric connector 93 to control the relief pressure of the discharging conduit 73.