The Jonggrangan Formation is one of the carbonate rock units of West Progo Hill exposed in Brajan, Banjararum, West Progo. The aim of this study is determining the environment and depositional mechanism of the lower Jonggrangan Formation at Brajan, Banjararum, West Progo. Petrographic analysis was used to find out the standard of microfacies while paleontological analysis have been done to determine the age and sedimentary environment. Based on stratigraphic measurement section at Brajan area, the lower Jonggrangan Formation is generally dominated by limestones, sandy limestone and intercalation of calcareous sandstone. Results of petrographic analysis show that the type of rocks are floatstone, packstone, sandy lime packstone, sandy lime wackestone and calcareous lithic arenite. The results of standard microfacies analysis show that the rocks have been deposited on the foreslope (SMF5/FZ4), deep shelf margin (SMF5/FZ3) and open sea shelf (SMF9/FZ2) environments. Paleontological data indicates that sedimentary rocks deposited during the Early Miocene to lower Middle Miocene (N5-N9) in inner–middle neritic environment.