Sediment causes serious water problems, including flooding, water pollution, and other issues related to water sediment. The data found that 82% of the 550 rivers in Indonesia were polluted and in critical condition. Hence, river maintenance is essential, especially for monitoring the existence of river sediment. This research makes a device to monitor sediment in the river and measure its volume. The device consists of a small boat in which an Arduino Mega 2560 RS microcontroller was an Arduino Mega 2560 RS microcontroller which will control sensors, motors, and a rotary encoder in monitoring and measuring sediment. This paper explained how Arduino could move the boat looking for sediment, detect sediment with infrared sensors, raise and lower the sensor by adjusting the motor in front and behind the boat and finally calculate the volume of sediment. The electronic circuits, block diagrams, and programs used are described in detail in this paper and discuss sensor accuracy and accuracy of measurement results. The result is the device can detect the sediment, measure the height of the sediment, trace the sediment to measure its length, and then rotate to measure the width of the sediment. All movements are carried out by utilizing the capabilities of Arduino. The PID algorithm can precisely determine the initial position of the sensors. It can detect sediment accurately. The measurement results show that the device can work well with a relatively small error.