This research is based on how the teacher builds a learning motivation of 5-6 years old children. In the classroom, sometimes children's motivation decrease, there is one way to build learning motivation on children, it is called positive reinforcement. This research aims to determine the learning motivation of 5-6 years old children by giving positive reinforcement in the math and science subject. The method of this research was qualitative descriptive with the sample was six students of B2 class around 5-6 years old at the kindergarten in the Purwakarta, Indonesia. The instrument of the research was an observation sheet of students and teachers' activities and the interview. The result of the data analysis on teacher's observation was a positive reinforcement from the teacher by giving children praise; nonverbal reinforcement was delivered by smiling at children, showing a cheerful face and thumbs. Moreover, the result of observation also showed that children more like if the teacher gives praise in words forming for what they are doing, so the good behavior will continuous appear.