The foundry sand binder supply apparatus of the present invention comprises a hopper for storing a binder therein, a binder transfer device for transferring the binder, a binder measuring and discharging device disposed beneath a distal end of the binder transfer device, and a binder supply amount control device. The binder measuring and discharging device comprises a measuring container for receiving the binder therein, a load cell for measuring the weight of the binder inside the measuring container, and a discharge device for discharging the binder from the measuring container. The binder supply amount control device is operable to control the discharge device to discharge the binder from the measuring container by a predetermined amount less than the whole amount of the binder inside the measuring container, and control the binder transfer device to supply the binder into the measuring container by the predetermined amount of the discharged binder.