The present invention aims to provide biodegradable particles for medical use and a vascular embolization material which have improved flexibility, cause less aggregation among particles, and have improved particle shape-recovering ability after passing through a catheter or the like. The present invention provides biodegradable particles for medical use composed of an A1-B-A2 type triblock copolymer, wherein A 1 and A2 are each a block of biodegradable copolymer constituted by monomers comprising glycolic acid, lactic acid and 6-hydroxycaproic acid, and B is a block of water-soluble polymer.
