The purpose of this study was to know the impact of the utilization of android applications in learning mathematics in SMPN-1 Sragen. This classroom action research was conducted in two cycles,each cycle beginned with planning, action, observation, and reflection. The data in this study was the assessment of the learning process obtained from learners in the activity and assessment at the end of the cycle. Then, the data was analyzed to know whether the utilization of android application in teaching space has been successful or not. There was an increase in students' learning achievement in understanding mathematics after having utilized the android applications. Before the action, only 18 students (56.25%) completed their learning and increased to be 22 students (68.75%) on the first cycle. In the second cycle, the number of students completed their learning was 31 students (96.87%). The use of android application for class IX students B SMPN-1 Sragen had improved the students' learning achievement. Before the action, the average knowledge of students was 75.16 and their average skill was 70.63. In the first cycle, the average knowledge of students is 78.59 and their average skills is 72.5. In the second cycle, of average knowledge 88.13 average skills 86.88. The conclusion, the utilization of android application in teaching the space learning content improved the students learning achievement. Teachers are suggested to utililize the android application or other appropriate media in learning-teaching activities.