A swaging tool for fastening a portion to be fastened, wherein the swaging tool is configured to move a collar fitted to a pintail side of a fastening pin toward a pinhead side so as to bring the collar into contact with the portion to be fastened, the pinhead of the fastening pin being positioned on one side of the portion to be fastened through which the fastening pin is inserted and the pintail of the fastening pin being positioned on another side of the portion to be fastened, to swage the collar to the fastening pin with the collar being in contact with the portion to be fastened, and to apply a tensile load to the pintail to break off and remove the pintail, the swaging tool comprising: a holding member configured to hold the pintail of the fastening pin; a swaging member having a swaging die formed therein, wherein the swaging die is configured to come into contact with and swage the collar; and a stroke mechanism which is configured to expand and contract a space between the swaging member and the holding member, wherein the stroke mechanism includes a rotatable rotary member and is configured to convert a rotation of the rotary member to an expansion and contraction of the space between the holding member and the swaging member and to restrict a rotation of the swaging member and a rotation of the holding member, characterized in that the stroke mechanism is provided adjacent to the holding member and the swaging member, and the stroke mechanism further includes: a first extending portion extending outwardly from a housing member, the housing member being provided between the holding member and the swaging member, the housing member being configured to house the holding member therein; a second extending portion extending from the swaging member so as to face the first extending portion with a predetermined gap; and a guide member extending from the first extending portion to the second extending portion through the gap, wherein the rotary member is configured to be screwed with the guide member positioned in the gap, the rotation of the rotary member with respect to the guide member expanding and contracting a space between the first extending portion and the second extending portion. a holding member configured to hold the pintail of the fastening pin; a swaging member having a swaging die formed therein, wherein the swaging die is configured to come into contact with and swage the collar; and a stroke mechanism which is configured to expand and contract a space between the swaging member and the holding member, wherein the stroke mechanism includes a rotatable rotary member and is configured to convert a rotation of the rotary member to an expansion and contraction of the space between the holding member and the swaging member and to restrict a rotation of the swaging member and a rotation of the holding member, characterized in that the stroke mechanism is provided adjacent to the holding member and the swaging member, and the stroke mechanism further includes: a first extending portion extending outwardly from a housing member, the housing member being provided between the holding member and the swaging member, the housing member being configured to house the holding member therein; a second extending portion extending from the swaging member so as to face the first extending portion with a predetermined gap; and a guide member extending from the first extending portion to the second extending portion through the gap, wherein the rotary member is configured to be screwed with the guide member positioned in the gap, the rotation of the rotary member with respect to the guide member expanding and contracting a space between the first extending portion and the second extending portion. a first extending portion extending outwardly from a housing member, the housing member being provided between the holding member and the swaging member, the housing member being configured to house the holding member therein; a second extending portion extending from the swaging member so as to face the first extending portion with a predetermined gap; and a guide member extending from the first extending portion to the second extending portion through the gap, wherein the rotary member is configured to be screwed with the guide member positioned in the gap, the rotation of the rotary member with respect to the guide member expanding and contracting a space between the first extending portion and the second extending portion.