Effective disaster management lead to useful and reliable mitigation program. Mitigation program is an action to reduce the risk to life, property, social and economic activities, etc. from natural disasters. One of the most often disasters that occurred in Indonesia is a tsunami. Tsunami also had a lot of victims, including life victims, house, property, etc. This article focuses on using design thinking method as an approach to developing a mobile application for tsunami disaster management in Indonesia. The first step of the design thinking is empathizing with the user, which we have done by with the victims of the tsunami by interviewing one of the survivors. The second step is defining the user's needs. In the third step, ideation, we are doing brainstorming by using an affinity diagram. After that, we are developing the prototype by developing the beta version of the application to visualize the interfaces. Lastly, in the testing step in validating our mobile application prototype, we visited one of the schools in Banten which had experienced a tsunami disaster. In the end, we are discussing the results including from the pre-Test and post-Test results from students who had tried our application.