Shaking Water Bath is a tool used for the heating process or incubation sample of the solution as well as mixed. The Shaking Water Bath that is used so far still has a manual water drainage system, so the officer must turn over the device to dispose of water and there is a possibility the officer is exposed to hot water, therefore a Shaking Water Bath tool is designed that can automatically fill and discharge water. The design of this tool uses a emmercion heater as a water heater in the chamber and the temperature in the chamber will be detected by the LM35 sensor. The temperature value detected by the LM35 sensor will be displayed on the 4x20 character LCD. This designed tool is also equipped with a filling and discharging system water automatically through the selenoid valve which is controlled by a microcontroller. The test is done by comparing the values displayed on the LCD with a stopwatch meter for the timer parameters and a thermometer for the temperature parameters. Timer and temperature testing data were carried out 20 times and mixing testing was carried out 3 times with different ingredients. Based on the measurement results on the timer and temperature testing, an error value of 0.017% was obtained for the 5 minute timer test, 0.22% for the 10 minute timer, 0.13% for the 15 minute timer, 0.38% for 37 ° C temperature testing, 0 , 22% at 45 ° C and 0.37% at 55 ° C. The results of the mixing and disposal test show that the tool can mix 2 ingredients and the tool can discharge water automatically according to the settings in the program. Based on the test data, it can be concluded that the "Shaking Water Bath" tool can work well and is suitable for use