Low tire pressure can have adverse effects on a vehicle, such as abnormal tire wear, increased tire rolling loss, tire burst due to excessive heat generated, poor running stability due to reduced cornering power, and hydroplaning phenomenon.The purpose of a low tire pressure warning device is to give adequate warning to a driver when tire pressure falls below the specified level, calling attention to the need for countermeasures, such as adding tire pressure or tire repairs. Thus, the equipment is to reduce the adverse effects of low tire pressure, insure safer operation, and achieve better economy.For this, various warning devices have been developed and reported. The tire pressure warning system presented in this paper was developed to incorporate a user-friendly feature that would tell the driver which of the four wheels has low tire pressure, combined with low system price.To achieve these targets, a combination of magnet and Hall effect IC was selected for transmitting change in tire pressure from a rotating and vibrating tire, which also resulted in a simple control circuit.The main components of the system are a pressure sensor using a magnet. Hall effect IC, control circuit, and alarm section, operating as follows: A pressure sensor is mounted on each wheel disc. When pressure falls, the magnet of the pressure sensor, as it rotates, causes a change in the magnetic field it generates. Each time the wheel rotates, the magnet moves across the Hall effect IC mounted on a suspension member. The IC then detects the change in the magnetic field and signals the control circuit. The control circuit identifies the wheel generating the signal, then operates the alarm to warn the driver.