A method for suppressing shock and storage cracking when manufacturing seamless steel pipes comprises hot piercing and hot rolling a billet consisting of, by mass percent controlled amounts of C, Si, Mn, Cr, Mo, Ti, and Al, with the balance being Fe and impurities of Ni, P, S, N, and O also in controlled amounts. Further heat treatment is performed, wherein a hot rolled steel pipe is direct quenched from a temperature of not lower than the Ar3 transformation point and the pipe is then subjected to heat treatment at a temperature of not lower than 450° C. and not higher than the Ac1 transformation point in heat treatment equipment for performing direct quenching. The steel pipe subjected to the heat treatment is reheated, quenched from a temperature of not lower than the Ac3 transformation point, and tempered at a temperature of not higher than the Ac1 transformation point.