The present invention provides a belt length adjuster which makes it easy to carry out a belt length adjustment operation with eyewear or the like worn, has a simple structure, allows production costs to be reduced as well, and has the advantage of causing low fluid resistance during competitive swimming and the like because of compactness when used for swimming goggles. A belt length adjuster includes a belt pinching frame F, the belt pinching frame F including a first pinching frame 1 and a second pinching frame 2 pivotally intersecting each other, a crossing angle [alpha] between the first and second pinching frames 1 and 2 being able to be opened and closed, wherein a first end of a belt B is inserted into a first end of the belt pinching frame F and a second end of the belt B is inserted into a second end of the belt pinching frame F, the first end and the second end of the belt B are pinched between the first and second pinching frames 1 and 2 when the crossing angle [alpha] is fully closed, and the first end and the second end of the belt B are released from pinching when the crossing angle [alpha] is fully opened.[課題]提供一種帶長調節具，是在穿戴狀態中容易進行帶子長度調節的操作，而且構造簡單，可刪減生產成本，且體積較低，故作為游泳護目鏡用的情況，在競泳等的流體抵抗較小而變得有利。 [解決手段]成為使第一夾持框（1）與第二夾持框（2）交差地旋動自如，且可使兩夾持框（1、2）擴張至交差角（α），或是閉合該交差角（α）的帶子夾持框（F），於該帶子夾持框（F）的一端插通帶子（B）的一端，於帶子夾持框（F）的另一端插通帶子（B）的另一端，在閉合前述交差角（α）時，使帶子（B）的一端與另一端被夾持在第一、二夾持框（1、2）之間，在擴張至前述交差角（α）時，使前述帶子（B）之一端與另一端的夾持被解除。
