The present invention receives an optical signal relates to an electronic water meter using an optical sensor to avoid measurement errors caused by disturbance such as electromagnetic waves or the static magnetic field, the light emitting the infrared light signals and reflected in order to accurately detect the water amount a light sensor for detecting the number of revolutions of the impeller, also the impeller, the detected from the optical sensor determines the flow rate depending on the number of revolutions of the impeller, and this real-time accumulation and the calculated time slot usage and yesangryang is rotated according to the flow rate of the meter calculation, and thus time slot accumulation, and display the estimated immediately before the time the operating flow rate, immediately after the time the flow rate and the communication state through the LCD display unit, the central control unit, the center to transmit the flow rate information calculated by controlling the communication unit to the external device memory to store all types of information that are processed by the control device, at the central control apparatus The computed time slot accumulation, just before the time the operating flow rate, immediately after the time estimated flow rate and the LCD display unit to display the communication state, and a wireless or wired to the flow rate information calculated in the central control device, the communication comprises a communication device for transmission to an external device. Therefore, as by the disturbance no effect on the instrument error light not a chance error occurs in any disturbance to detect the number of revolutions of the impeller by weighing accumulates the usage amount of water, and so the amount used can be appropriately saved, the value metering remotely by enabling meter reading (wired or wireless) may maximize the efficiency at a reasonable quantitative commerce.