It is intended to provide a milnacipran formulation which is more stable than a conventionally known milnacipran formulation, and a method of stabilizing a milnacipran formulation. The object could be achieved by using a milnacipran-containing composition in which milnacipran or a salt thereof is allowed to exist in a porous carrier, packing a powder containing milnacipran or a salt thereof in an HPMC capsule, or combining an additive which does not cause an interaction with milnacipran with time.
