PROBLEM TO BE SOLVED: To provide microparticles that comprise a crosslinked polymer expressing excellent resistance against physical impacts.SOLUTION: There is provided microparticles that comprise a crosslinked polymer, which polymer is composed of a crosslinkable compound represented by formula (1) wherein X, Y. Z, R-Rare each a specific group. The microparticles are usable as a delivery system for active material, especially drugs, diagnostic assistants or assistants for contrast media.【課題】物理的衝撃に対して良好な耐性を示す架橋ポリマーを含む微粒子の提供。【解決手段】式で示される架橋性化合物からなる微粒子。式中、X、Y、Z、R0~R3は特定の基。本微粒子は、活性物質、特に薬剤、診断助剤または造影助剤の輸送システムとして使用し得る。【選択図】なし