A treatment instrument which is provided with: a long shaft member comprising a longitudinal shaft a collection member provided at the tip end of the long shaft member and comprising an opening part and a housing part communicating with the opening part a frame part which is provided on the rim of the opening part and defines the shape of the opening part a capacity adjustment member which connects with the collection member and/or the frame part, and adjusts the capacity of the housing part a capacity operation member which connects with the capacity adjustment member, is positioned along the longitudinal shaft and is provided to be able to advance/retreat in the longitudinal shaft direction with respect to the long shaft member an opening operation member which connects with the frame part, is positioned along the longitudinal shaft and is provided to be able to advance/retreat in the longitudinal shaft direction with respect to the long shaft member independently of the advance/retreat of the capacity operation member with respect to the long shaft member and an operation means which causes the opening operation member and the capacity operation member to advance/retreat in the longitudinal shaft direction independently of each other.Linvention concerne un instrument de traitement qui comporte: un élément de tige allongé comprenant une tige longitudinale un élément de collecte disposé à lextrémité de pointe de lélément de tige allongé et comprenant une partie douverture et une partie de boîtier communiquant avec la partie douverture une partie de cadre qui est disposée sur le rebord de la partie douverture et définit la forme de la partie douverture un élément dajustement de capacité qui est relié à lélément de collecte et/ou à la partie de cadre, et ajuste la capacité de la partie de boîtier un élément de fonctionnement de capacité qui est relié à lélément dajustement de capacité, est positionné le long de la tige longitudinale et est prévu pour être apte à
