To provide a pharmaceutical technique which inhibits yellowing caused under temporal or high temperature conditions, while containing diclofenac and/or a salt thereof and tocopherol and/or a derivative thereof, in an external pharmaceutical composition which contains water, to enable having an excellent storage stability. In an external pharmaceutical composition containing diclofenac and/or a salt thereof, tocopherol and/or a derivative thereof, and water, containing lactic acid and/or a salt thereof can inhibit yellowing caused under temporal or high temperature conditions to enable having an excellent storage stability.