A coating material for a solid formulation is capable of stably retaining the effective ingredient in the solid formulation for a prolonged period even in unpacked condition in such a manner that the solid formulation can be used in a single-dose formulation. The coating material for a solid formulation includes a high hydrogen-bonding resin and a swelling clay and, when coated on a solid formulation and dried, forms a coating film in which the laminated structures of the aforementioned swelling clay are oriented planarly and dispersed in a network fashion.
