A shift control system for an industrial vehicle includes: a vehicle speed detection device that detects a vehicle speed; a transmission device that shifts up and shifts down a speed stage of a transmission; a shift control device that permits shift up when a vehicle speed becomes equal to or greater than a shift up permission vehicle speed; a height position detection device that detects a height position of a working machine device; a forward/backward switch device that switches the industrial vehicle between forward travel and backward travel; and a shift up control switch selection device that switches between normal control, in which shift up is performed by the transmission device when the vehicle speed becomes equal to or greater than the shift up permission vehicle speed, and delay control, in which shift up timing is delayed with respect to the normal control.