A shift control system for industrial vehicle, comprising: a vehicle speed detection device that detects a vehicle speed of an industrial vehicle; a transmission device that shifts up and shifts down a speed stage of a transmission; a shift control device that permits shift up by the transmission device when a vehicle speed detected by the vehicle speed detection device 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 (111, 112); 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, characterized in that speed stages at the transmission include 3 speeds or more; when the delay control has been selected by the shift up control switch selection device, when forward travel is selected by the forward/backward switch device; the shift control device sets the shift up permission vehicle speed to a first shift up permission vehicle speed if a height position of the working machine device (111, 112) that is detected by the height position detection device is lower than a setting value, and sets the shift up permission vehicle speed to a second shift up permission vehicle speed that is greater than the first shift up permission vehicle speed if a height position of the working machine device (111, 112) is equal to or greater than the setting value; and when a height position of the working machine device (111, 112) is equal to or greater than the setting value, the shift control device controls the transmission device so that a speed stage at the transmission is shifted up from speed 2 to speed 3 if the vehicle speed has continued to be equal to or greater than the second shift up permission vehicle speed for a forward travel setting time. a vehicle speed detection device that detects a vehicle speed of an industrial vehicle; a transmission device that shifts up and shifts down a speed stage of a transmission; a shift control device that permits shift up by the transmission device when a vehicle speed detected by the vehicle speed detection device 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 (111, 112); 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, characterized in that speed stages at the transmission include 3 speeds or more; when the delay control has been selected by the shift up control switch selection device, when forward travel is selected by the forward/backward switch device; the shift control device sets the shift up permission vehicle speed to a first shift up permission vehicle speed if a height position of the working machine device (111, 112) that is detected by the height position detection device is lower than a setting value, and sets the shift up permission vehicle speed to a second shift up permission vehicle speed that is greater than the first shift up permission vehicle speed if a height position of the working machine device (111, 112) is equal to or greater than the setting value; and when a height position of the working machine device (111, 112) is equal to or greater than the setting value, the shift control device controls the transmission device so that a speed stage at the transmission is shifted up from speed 2 to speed 3 if the vehicle speed has continued to be equal to or greater than the second shift up permission vehicle speed for a forward travel setting time.