Experiments on the solubilization of slightly soluble phosphate in the rhizosphere by organic acids secreted from wheat seedlings (Triticum aestivum L.) were performed and the following results were obtained. 1) Solubilization of aluminum and ferric phosphate by the extracts from the rhizosphere soil of wheat seedlings grown in Akadama soil (reddish soil located under volcanic ash soil, treated by 800℃) was confirmed. The lower the phosphate level in the soil where the wheat was grown, the more phosphate was so1ubi1ized by the extract from the rhizosphere soil. 2) Organic acids in the rhizosphere soil extract were identified as oxalate, citrate, malate and fumarate by liquid chromatography. Malate showed the highest amount among the organic acids detected. 3) The effluent from the soil column containing malate contained more aluminum and ferric ions in the earlier fractions, and then the content decreased with the gradual increase of phosphate. 4) Competition assay with hematoxylin suggested the formation of a chelate compound of aluminum in the soil with organic acids secreted from the roots and release of phosphate from aluminum phosphate. It was concluded that organic acids secreted from wheat seedlings reacted with aluminum in the rhizosphere soil and released phosphate from aluminum phosphate.