The depletion of phosphorus as essential fertilizer is becoming a serious problem. This paper reports the controlled release of phosphate using silica microcapsules to contribute the efficient use of phosphate fertilizer. When silica microcapsule encapsulating Ca-3(PO4)(2) was modified with dodecylsilyl groups, the release of phosphate into acidic water was prolonged significantly. The controlled release of quick-acting fertilizer was also achieved by the modified microcapsule.