To ensure excellent image quality and to improve the stain, particular dye stain of a film by supplying an oxidizing agent-contg. thick soln. or solid agent while mixing with water in a washing tank after a fixing step when a silver halide photographic sensitive material contg. a specified spectral sensitizing dye is washed after it is imagewise exposed, developed and fixed.

When a silver halide photographic sensitive material contg. a spectral sensitizing dye represented by the formula is washed with oxidizing agent-contg. washing water after it is imagewise exposed, developed and fixed, an oxidizing agent-contg. thick soln. or solid agent is supplied while mixing with water in a washing tank after the fixing step. In the formula, each of Z11 and Z12 is a group of nonmetallic atoms required to complete a 5- or 6-membered nitrogen-contg. heterocycle, each of R11 and R12 is alkyl or aryl, each of Q11 and Q12 is a group of nonmetallic atoms, each of L11-L15 is methine or substd. methine, each of n11-n13 is 0 or 1, X1 is an ion required to compensate an electric charge of each molecule and m1 is the number required to neutralize all electric charges of each molecule.