The present invention relates to a ligand-drug conjugate including a ligand; a linker that is connected to the ligand by a covalent bond and has a tris structure represented by a specific structural formula; and an active agent connected to the linker by a covalent bond. In the ligand-drug conjugate, the active agent is bound by the tris structure of the linker, and thus a greater number of active agents can be connected through one linker. Accordingly, a greater number of active agents per antibody binding can be delivered to the target cell, and the drug and/or toxin can stably reach the target cell and effectively exert the drug efficacy.