Abstract: A lead line adjusting device for a companion animal is provided. The lead line adjusting device for a companion animal includes a cover part configured to include a plurality of locking means; a rotating member around which a lead line is wound; a plurality of latches configured to be coupled to one side surface of the rotating member and opened so as to be caught by a portion of the plurality of locking means while rotating about the same shaft as the rotating member when a force greater than or equal to a predetermined reference is applied to the lead line; and a spiral spring configured to apply a rotational force so that the lead line is wound around the rotating member. Accordingly, it is possible to automatically control the lead line in both directions, such as when the lead line is wound or when the lead line is unwound.