A solution for extracting substantially pure RNA from a biological sample is disclosed. The solution for extracting RNA from a biological sample containing RNA and at least DNA comprises: (a) phenol in an amount of more than 50% by volume based on the total amount of the solution; (b) a polyol in an amount of 3 to 10% by volume based on the total amount of the solution; (c) a guanidinium salt at a concentration of 0.5 to 2.0 M based on the total amount of the solution; (d) a thiocyanate at a concentration of 0.1 to 0.5 M based on the total amount of the solution; and (e) a buffer for maintaining the pH of the solution at 4 to 6.