A method for producing a block copolymer composition composed of a block copolymer A represented by a formula and a block copolymer B represented by a formula, a weight ratio (A/B) of the block copolymer A to the block copolymer B in the block copolymer composition being 36/64 to 85/15, a ratio of an aromatic vinyl monomer unit with respect to a total polymer component included in the block copolymer composition being 27 to 70 wt%, and the block copolymer composition having a water content of 200 ppm by weight or less when the block copolymer composition has been formed in a shape of pellets, dried, and allowed to stand at a temperature of 37°C and a relative humidity of 70% for 24 hours, Ar1 a -D a -Ar2 a Ar1 b -D b -Ar2 b wherein each of Ar1 a, Ar1 b, and Ar2 b is independently an aromatic vinyl polymer block having a weight average molecular weight of 6,000 to 18,000, Ar2 a is an aromatic vinyl polymer block having a weight average molecular weight of 40,000 to 400,000, and each of D a and D b is independently a conjugated diene polymer block having a vinyl bond content of 1 to 20 mol% and a weight average molecular weight of 40,000 to 400,000, the method comprising: a step that polymerizes an aromatic vinyl monomer in a solvent using a polymerization initiator to obtain a solution including an aromatic vinyl polymer having an active terminal; a step that adds a conjugated diene monomer to the solution including the aromatic vinyl polymer having an active terminal that has been obtained by the step, and polymerizes the conjugated diene monomer to obtain a solution including an aromatic vinyl-conjugated diene block copolymer having an active terminal; a step that adds an aromatic vinyl monomer to the solution including the aromatic vinyl-conjugated diene block copolymer having an active terminal that has been obtained by the step, and polymerizes the aromatic vinyl monomer to obtain a solution including an aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having an active terminal; a step that adds a polymerization terminator to the solution including the aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having an active terminal that has been obtained by the step in a ratio of less than 1 molar equivalent with respect to the active terminal to partly inactivate the active terminal of the aromatic vinyl-conjugated diene-aromatic vinyl block copolymer to obtain a solution including the block copolymer B; a step that adds an aromatic vinyl monomer to the solution including the block copolymer B that has been obtained by the step, and polymerizes the aromatic vinyl monomer to obtain a solution including the block copolymer B and the block copolymer A; and a step that collects the block copolymer composition from the solution including the block copolymer B and the block copolymer A that has been obtained by the step. a step that polymerizes an aromatic vinyl monomer in a solvent using a polymerization initiator to obtain a solution including an aromatic vinyl polymer having an active terminal; a step that adds a conjugated diene monomer to the solution including the aromatic vinyl polymer having an active terminal that has been obtained by the step, and polymerizes the conjugated diene monomer to obtain a solution including an aromatic vinyl-conjugated diene block copolymer having an active terminal; a step that adds an aromatic vinyl monomer to the solution including the aromatic vinyl-conjugated diene block copolymer having an active terminal that has been obtained by the step, and polymerizes the aromatic vinyl monomer to obtain a solution including an aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having an active terminal; a step that adds a polymerization terminator to the solution including the aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having an active terminal that has been obtained by the step in a ratio of less than 1 molar equivalent with respect to the active terminal to partly inactivate the active terminal of the aromatic vinyl-conjugated diene-aromatic vinyl block copolymer to obtain a solution including the block copolymer B; a step that adds an aromatic vinyl monomer to the solution including the block copolymer B that has been obtained by the step, and polymerizes the aromatic vinyl monomer to obtain a solution including the block copolymer B and the block copolymer A; and a step that collects the block copolymer composition from the solution including the block copolymer B and the block copolymer A that has been obtained by the step.