A locking member of a suture locking device includes a loop portion formed in an α-shape when viewed from a width direction, and a pair of extensions extending from the loop portion towards a distal side, and an intersection portion in which the pair of extensions intersect is formed at a distal end of the loop portion. The loop portion is inserted into the hollow portion from the distal side with the thread being inserted through an inner space of loop portion, and the thread is pulled from a proximal side towards the intersection portion in the inner space of the loop portion so that the thread is locked to the loop portion.