A tissue resection apparatus includes a pair of grasping members that holds a tissue and a cartridge that is replaceably attached to the pair of grasping members. The cartridge includes a cartridge body that has a longitudinal axis and a slot extending along the longitudinal axis, guides a cutting member cutting a tissue by the slot, and defines a movement range of the cutting member a pair of sealing portions that are provided on both sides of the slot so as to sandwich the slot and extend parallel to the slot, respectively and a tissue sealing portion that is located closer to a distal end side than the slot and is provided on an extension line of the slot.
