This brake adjustment monitoring device, serves to warn the operators of trucks, buses and other vehicles, when their brakes are in need of adjustment or repair, which will effectively cut down the number of accidents caused by brakes being out of adjustment. Primarily, the device consists of a magnet adjustably secured to the shaft of the diaphragm within each air chamber. It also includes a block with a reed switch in it that is in cooperation with the magnet, so as to close the switch by magnetic force when the shaft of the air chamber moved outward too far, when the operator touches the brake pedal of the vehicle. It further includes a cab mounted indicator unit, having a buzzer and a bulb for alerting the operator when the brakes are in need of adjustment.