Research'sain is to know the influence of baby gym to the development of rude motorik and soft motorik in baby's age 4-12 months, in Kelurahan Mataram Timur, the reason is there is no research before. The research is by using quasi experimental approach with "Pretest-Post test with Control Group Design". Target population of health babies on 4-12 months that fill the vriteria inclusi and record in 5 posyandu. The result of selection from 162 babies, 38 respondence which is devide into 19 babies group of treatment and 19 babies group control. Collecting independent data by plan observation with checklist, and depedent data observation by DDST. Analysis that used is t-test in sample and one sample test in free with level P<0.05. The research are 19 babies intervention group and 19 babies control group, there is influence of baby gym and development of rude motorik baby who exercise and do not exercise with t-test. The result test P=0.000. There is influence in development of soft motorik baby who exercise and do not exercise with t-test. The result test P=0.001. There is deference between development of rude motorik and soft motorik in post intervention group and control group with the valve of P=0.000 which is meaningfil. From this research we hope for all of official medic can give socialization about healty gyn for all mothers who have bany onclude bursing student