A sustained-release composition which comprises (i) a physiologically active substance and (ii) a lactic acid-glycolic acid copolymer in which the weight-average molecular weight (Mw) is about 8,000 to about 11,500, the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) is greater than 1.9, and the compositional molar ratio of lactic acid to glycolic acid is 99.9/0.1 to 60/40, or a salt thereof, and which does not contain a drug retaining substance is provided and said sustained-release composition has improved spherical property and/or needle penetrating property.
