The present invention provides a preparation which is a sustained-release preparation capable of providing a dissolution profile that permits once-daily administration even in the case of a highly water-soluble drug, and which can exhibit stable drug dissolution behavior and can be reduced in its size； and a method for producing the same. A preparation containing a highly water-soluble drug, a gel-forming polymer, and a low-melting lipophilic substance is usable as a sustained-release preparation that permits once-daily administration, and enables reduction in its size and simple production thereof, and thus, the objects have been achieved.
