The purpose of this research is to develop a probability program based on the actual condition of understanding of probability by the elementary school students from 3rd to 6th grade and search for ways to apply it to the 3rd grade of elementary school students. Based on the results from the research, the author reached a conclusion as following. After applying the learning program to five students of 3rd grade, all of the five students made progress understanding the concept of experimental and theoretical probability. However, for understanding the concept of example space, only two leading students were improved, which shows that students are having much difficulty in understanding the concept. As for under-standing the concept of experimental probability, many students gained the conceptual difference between the experimental and theoretical probability after using the program and enhanced their understanding of experimental probability.