To provide an oil supply device which does not require to replenish oil from an another oil supply device when an oil storage tank has become vacant and hence, by which oil is not scattered.

This oil supply device is constituted of an oil storage part 10 provided with a housing 12 having a fork-insertion opening 11 at the lower part and a main tank 13 fitted to the housing 12, and a measuring part 20 provided with a subtank 22 installed in a case 21, a pump 33 and a flow rate meter 35 interposed in the oil-supply pipe 29 connected to the discharge opening of the subtank 22, an oil-supply hose 36 connected to the oil-supply pipe 29, and an oil-supply nozzle 38 attached to the front end of the oil-supply hose 36. The outflow pipe 17 of the main tank 13 and the inflow pipe 24 of the subtank 22 are connected to each other through detachable couplings 19, 27.