PROBLEM TO BE SOLVED: To provide a miniaturized formulation of ambroxol hydrochloride which is easy to ingest for children or seniors with reduced swallowing function, and has the assured efficacy and safety as a once-daily sustained release formulation.SOLUTION: The invention provides a drug sustained-release solid preparation containing a granule having a layer structure of at least three layers which comprise a first layer comprising a nuclear particle, ambroxol hydrochloride coating the nuclear particle, disintegrator, and a binder, a second layer comprising a water-insoluble polymer and a water-soluble polymer, and a third layer which may contain ambroxol hydrochloride and contains a binder, wherein the amount of ambroxol hydrochloride contained in the first layer is five times or more of the amount of ambroxol hydrochloride contained in the third layer even if ambroxol hydrochloride is contained in the third layer.
