Phosphate solubilizing microbes (PSM) are beneficial soil microbes that they have the ability to dissolve unavailable soil P into available and can mineralize organic P into inorganic P. The experiment was conducted to study the effect of phosphate solubilizing microbes on soil P, yield of upland rice plants and the efficiency of P fertilizer on marginal soil. Design experiment of Randomized Block Design (RBD) was used in field experiment, consisted of two factors and three replications. Phosphate solubilizing microbe as the first factor consisted two levels i.e without and with PSM (a mixture of Pseudomonas sp. and Penicillium sp.). While the second factor was P fertilizer consists four levels ((0, 50, 75 and 100 kg P2O5 ha-1). The result of experiment showed that PSM improved soil phosphatase activity and yield of upland rice on marginal soil. Phosphate solubilizing microbe increased soil organic P mineralization was characterized by a decrease in organic P. Inoculation of PSM with phosphate fertilizer dose of 75 kg P2O5 ha-1 (75% recommended dose) gave best effect to soil phosphatase activity, soil P status and yield of upland rice in marginal soil.