A mouth cleaning device nozzle, comprising: a bristle bundle at a distal end portion in a longitudinal direction of the mouth cleaning device nozzle, wherein a protruding direction of the bristle bundle is in an angular range of 85° to 95° with respect to the longitudinal direction; the bristle bundle includes a bristle portion and a bristle transplantation portion, the bristle portion including bristles; the distal end portion ejects a liquid to an outside through the bristle transplantation portion of the bristle bundle; the bristle transplantation portion is a base of the bristle portion; the mouth cleaning device nozzle further comprises a nozzle handle that comprises the distal end portion, and is along the longitudinal direction; characterized in that the mouth cleaning device nozzle further comprises a bristle bundle holder that holds the bristle bundle inside the distal end portion; the bristle bundle holder has a fitting portion press-fitted into an inner wall of the distal end portion and an engagement shaft pushed into a through hole formed in the bristle transplantation portion; the distal end portion comprises a first opening portion having an inner periphery smaller than an outer periphery of the bristle transplantation portion and a second opening portion facing the first opening portion and having an inner periphery larger than the outer periphery of the bristle transplantation portion; the bristle bundle and the bristle bundle holder are introduced into the inside of the distal end portion from the second opening portion toward the first opening portion in the protruding direction of the bristle bundle; and the engagement shaft is engaged with the through hole formed in the bristle transplantation portion, a part of an outer peripheral portion of the bristle transplantation portion is fitted into the inner wall of the distal end portion and a part of the fitting portion is fitted into the inner wall of the distal end portion so that the bristle bundle and the bristle bundle holder are attached to the distal end portion. a bristle bundle at a distal end portion in a longitudinal direction of the mouth cleaning device nozzle, wherein a protruding direction of the bristle bundle is in an angular range of 85° to 95° with respect to the longitudinal direction; the bristle bundle includes a bristle portion and a bristle transplantation portion, the bristle portion including bristles; the distal end portion ejects a liquid to an outside through the bristle transplantation portion of the bristle bundle; the bristle transplantation portion is a base of the bristle portion; the mouth cleaning device nozzle further comprises a nozzle handle that comprises the distal end portion, and is along the longitudinal direction; characterized in that the mouth cleaning device nozzle further comprises a bristle bundle holder that holds the bristle bundle inside the distal end portion; the bristle bundle holder has a fitting portion press-fitted into an inner wall of the distal end portion and an engagement shaft pushed into a through hole formed in the bristle transplantation portion; the distal end portion comprises a first opening portion having an inner periphery smaller than an outer periphery of the bristle transplantation portion and a second opening portion facing the first opening portion and having an inner periphery larger than the outer periphery of the bristle transplantation portion; the bristle bundle and the bristle bundle holder are introduced into the inside of the distal end portion from the second opening portion toward the first opening portion in the protruding direction of the bristle bundle; and the engagement shaft is engaged with the through hole formed in the bristle transplantation portion, a part of an outer peripheral portion of the bristle transplantation portion is fitted into the inner wall of the distal end portion and a part of the fitting portion is fitted into the inner wall of the distal end portion so that the bristle bundle and the bristle bundle holder are attached to the distal end portion.