The endoscopic treatment instrument includes an insertion portion; a treatment portion; and a control portion. The treatment portion includes a pair of forceps members; a tip cover; a distal end holding portion that is fixed to a distal end of the insertion portion; a distal end locking member that restrains a relative movement by locking the tip cover onto the distal end holding portion; and a distal end release member that is provided on an operational member by which the pair of forceps members is opened and closed and that releases an engagement made by the distal end locking member between the tip cover and the distal end holding portion at least when the pair of forceps members is closed.