An automatic vehicle wiper system including a wiper, a speed sensor which measures vehicle speed, a rainfall measuring device which measures amount of rainfall during predetermined intervals, a calculating device which calculates a wiping action frequency of the wiper as first data, depending on the amount of rainfall measured by the rainfall measuring device, a memory device which stores the first data calculated by the calculating device as second data when the vehicle speed measured by the speed sensor decreases to equal to or less than a predetermined value, and a wiping action frequency determining device which determines the wiping action frequency of the wiper by comparing the first data and the second data when the vehicle speed measured by the speed sensor becomes equal to or greater than a predetermined value after it has been confirmed that the vehicle has stopped.