An endoscopic treatment instrument (1; 801) comprising: an insertion portion having a distal end and a proximal end, the distal end being inserted into a human body; a treatment portion provided at the distal end of the insertion portion; and a control portion provided at the proximal end of the insertion portion; wherein the treatment portion includes: a pair of forceps members (115, 131); a tip cover (80; 810) which supports a pivot shaft that pivots at least one of the pair of forceps members (115, 131) openably and closably with respect to the other forceps member (131, 115); a distal end holding portion that is fixed to the distal end of the insertion portion and in which the tip cover (80; 810) is held relatively movably toward the distal end of the insertion portion and toward the proximal end of the insertion portion; wherein a distal end locking member (75; 843) that restrains a relative movement by locking the tip cover (80; 810) onto the distal end holding portion when the pair of forceps members (115, 131) is opened to grasp a specified object; and a distal end release member (105; 854) that is provided on an operational member by which the pair of forceps members (115, 131) is opened and closed and that releases an engagement made by the distal end locking member (75; 843) between the tip cover (80; 810) and the distal end holding portion at least when the pair of forceps members (115, 131) is closed. an insertion portion having a distal end and a proximal end, the distal end being inserted into a human body; a treatment portion provided at the distal end of the insertion portion; and a control portion provided at the proximal end of the insertion portion; wherein the treatment portion includes: a pair of forceps members (115, 131); a tip cover (80; 810) which supports a pivot shaft that pivots at least one of the pair of forceps members (115, 131) openably and closably with respect to the other forceps member (131, 115); a distal end holding portion that is fixed to the distal end of the insertion portion and in which the tip cover (80; 810) is held relatively movably toward the distal end of the insertion portion and toward the proximal end of the insertion portion; wherein a distal end locking member (75; 843) that restrains a relative movement by locking the tip cover (80; 810) onto the distal end holding portion when the pair of forceps members (115, 131) is opened to grasp a specified object; and a distal end release member (105; 854) that is provided on an operational member by which the pair of forceps members (115, 131) is opened and closed and that releases an engagement made by the distal end locking member (75; 843) between the tip cover (80; 810) and the distal end holding portion at least when the pair of forceps members (115, 131) is closed. a pair of forceps members (115, 131); a tip cover (80; 810) which supports a pivot shaft that pivots at least one of the pair of forceps members (115, 131) openably and closably with respect to the other forceps member (131, 115); a distal end holding portion that is fixed to the distal end of the insertion portion and in which the tip cover (80; 810) is held relatively movably toward the distal end of the insertion portion and toward the proximal end of the insertion portion; wherein a distal end locking member (75; 843) that restrains a relative movement by locking the tip cover (80; 810) onto the distal end holding portion when the pair of forceps members (115, 131) is opened to grasp a specified object; and a distal end release member (105; 854) that is provided on an operational member by which the pair of forceps members (115, 131) is opened and closed and that releases an engagement made by the distal end locking member (75; 843) between the tip cover (80; 810) and the distal end holding portion at least when the pair of forceps members (115, 131) is closed.