The present invention provides a dilator that can easily and smoothly open and close a plurality of fins together or individually, has excellent operability, durability, and simple structure.The dilator 100 is configured to include a dilator body (30) having a first fin (10) and a second fin (20), and a driving member (50). The first and second fins (10, 20) include a pair of arm portions (11a, 11b, 21a, 21b) and angle adjustment portions (12, 22). The opening and closing mechanism (40) is provided with a pair of handles (41a, 41b), each of the handles (41a, 41b) has a grip portion (46a, 46b) and an actuation portion (47a, 47b), and is provided at each actuation portion (47a, 47b) There is a pair of engaging protrusions (48a, 48a, 234b) of engaging recesses (134a, 134b, 234a, 234b) engaged with the base ends (14a, 24a) of the first fin (10) and the second fin (20) 48b).本發明提供一種可一起或個別地容易且順利進行複數個翼片之開閉、且操作性、耐久性優異、構成簡單之擴張器。將擴張器100構成為具備具有第1翼片（10）及第2翼片（20）之擴張器本體（30）、及打入構件（50）。第1、第2翼片（10、20）具備一對臂部（11a、11b、21a、21b）、及角度調整部（12、22）。開閉機構（40）具備一對手柄（41a、41b），各手柄（41a、41b）具有握柄部（46a、46b）及作動部（47a、47b），於各作動部（47a、47b）設置有卡合於第1翼片（10）及第2翼片（20）之基端部（14a、24a）之卡合凹部（134a、134b、234a、234b）之一對卡合突起（48a、48b）。
