Availability of water is a major factor in determining cropping patterns in irrigated rice fields. This study aims to develop a microcontroller-based automation concept that can later be applied to ensure the availability of irrigation water needed for plants. The application designed was an automatic irrigation system of paddy rice using a water pump irrigation method. This system consists of an Arduino as a data processor, Bluetooth, a smartphone and a water level sensor as a water detector. The software uses MIT App Inventor as a smartphone programming medium and Arduino IDE as a whole series programming. The pump will turn on when the on button on the smartphone and when the water has reached the height specified by the water level sensor, the water level sensor will decide the pump voltage.