The present inventors have intensively investigated in view of the above-mentioned conditions, and ultimately succeeded in producing a lactic acid polymer or salt thereof not readily causing the initial excess release, by reducing the content of a lactic acid polymer of lower molecular weight, particularly, that having a weight- average molecular weight of 5000 or less in an biodegradable polymer, and found that a controlled release preparation containing this lactic acid polymer or salt thereof can incorporate a physiologically active substance in unexpectedly high content and that a stable releasing speed for a long period of time can be achieved by suppressing the initial excess release. Further, the present inventors have found that if a physiologically active substance is incorporated in high content in a composition by allowing a physiologically active substance and hydroxynaphthoic acid to coexist in forming the composition and further both of them are enclosed in a lactic acid polymer or salt thereof, then, the physiologically active substance is released at a different speed from the releasing speed of a physiologically active substance from a composition formed of a physiologically active substance and hydroxynaphthoic acid prepared in the absence of a lactic acid polymer or salt thereof, and the releasing speed can be controlled by the property of the biodegradable polymer and the addition amount of hydroxynaphthoic acid, and even at high content, the initial excess release can be suppressed effectively and sustained release for a very long period of time can be achieved. The present inventors have further studied based on this knowledge, and completed the present invention as a result. Namely, the present invention provides (1). A controlled release composition comprising (1) a physiologically active substance or salt thereof in an amount of about 14% (w/w) to about 24% (w/w) based on the total composition weight, (2) hydroxynaphthoic acid selected from
