To provide a workbench leveling device at low cost, by which follow-up performance of the derricking operation of the workbench with the derricking operation of a boom can be improved, and the workbench is not inclined by the specified angle or more.

A bottom side oil chamber 23a of an upper leveling cylinder 23 and a bottom side oil chamber 22a of a lower leveling cylinder 22 are connected to each other by a bottom side leveling hose 31, and a rod side oil chamber 23b of the upper leveling cylinder 23 and a rod side oil chamber 22b of the lower leveling cylinder 22 are connected to each other by a rod side leveling hose 32. Pilot check valves 41, 42 are provided on both leveling hoses 31, 32, the pilot check valves 41, 42 are opened in the derricking operation of a boom, and respective oil chambers of the upper and lower leveling cylinders 22, 23 are communicated with each other.