To provide a method for isolating an RNA quickly and simply.

This method for isolating the RNA comprises a process of extracting the RNA with an organic solvent such as phenol, chloroform, etc., by suspending a specimen in an aqueous solution containing a salt and a buffering agent under an acid condition, and a recovering process of the RNA contained in an aqueous solution by an alcohol precipitation method. Since the method can obtain a high purity RNA in a small number of steps simply and rapidly, it is suitable for the simultaneous treatments of many specimens and a mechanization. Also, since the specimen is not treated with SDS (sodium dodecylsulfate), guanidine thiocyanate, etc., it is possible to isolate the RNA in a high degree of purification even from a biological specimen containing much starch. Therefore, the method is suitably used for the extraction of the RNA from a plant tissue containing much starch such as a seed, etc.