A tool system comprising: an impact rotary tool attachment (7; 7a; 7b; 7c); and an impact rotary tool to which the impact rotary tool attachment (7; 7a; 7b; 7c) is attached, wherein the impact rotary tool attachment (7; 7a; 7b; 7c) includes: an input shaft, to which rotational driving force is transmitted from a first output shaft of the impact rotary tool; a second output shaft, to which the rotational driving force is transmitted from the input shaft; a driving force conversion mechanism (9; 9a; 9b) configured to, when the rotational driving force is transmitted from the input shaft to the second output shaft, perform at least one operation selected from the group consisting of: translating a rotational axis of rotation produced by the rotational driving force; changing an angle defined by the rotational axis; and converting the rotational driving force into thrust driving force applied along the rotational axis: a housing to house the driving force conversion mechanism (9; 9a; 9b) at least partially; and an attachment mechanism configured to attach and fix the housing onto a tip portion of the impact rotary tool, and the impact rotary tool including: an impact mechanism; and a metallic case to house the impact mechanism at least partially, and the attachment mechanism being attached to the metallic case, and the impact mechanism including an anvil and a hammer configured to apply rotational impact to the anvil. an impact rotary tool attachment (7; 7a; 7b; 7c); and an impact rotary tool to which the impact rotary tool attachment (7; 7a; 7b; 7c) is attached, wherein the impact rotary tool attachment (7; 7a; 7b; 7c) includes: an input shaft, to which rotational driving force is transmitted from a first output shaft of the impact rotary tool; a second output shaft, to which the rotational driving force is transmitted from the input shaft; a driving force conversion mechanism (9; 9a; 9b) configured to, when the rotational driving force is transmitted from the input shaft to the second output shaft, perform at least one operation selected from the group consisting of: translating a rotational axis of rotation produced by the rotational driving force; changing an angle defined by the rotational axis; and converting the rotational driving force into thrust driving force applied along the rotational axis: a housing to house the driving force conversion mechanism (9; 9a; 9b) at least partially; and an attachment mechanism configured to attach and fix the housing onto a tip portion of the impact rotary tool, and the impact rotary tool including: an impact mechanism; and a metallic case to house the impact mechanism at least partially, and the attachment mechanism being attached to the metallic case, and the impact mechanism including an anvil and a hammer configured to apply rotational impact to the anvil. an input shaft, to which rotational driving force is transmitted from a first output shaft of the impact rotary tool; a second output shaft, to which the rotational driving force is transmitted from the input shaft; a driving force conversion mechanism (9; 9a; 9b) configured to, when the rotational driving force is transmitted from the input shaft to the second output shaft, perform at least one operation selected from the group consisting of: translating a rotational axis of rotation produced by the rotational driving force; changing an angle defined by the rotational axis; and converting the rotational driving force into thrust driving force applied along the rotational axis: a housing to house the driving force conversion mechanism (9; 9a; 9b) at least partially; and an attachment mechanism configured to attach and fix the housing onto a tip portion of the impact rotary tool, and the impact rotary tool including: an impact mechanism; and a metallic case to house the impact mechanism at least partially, and the attachment mechanism being attached to the metallic case, and the impact mechanism including an anvil and a hammer configured to apply rotational impact to the anvil. an impact mechanism; and a metallic case to house the impact mechanism at least partially, and the attachment mechanism being attached to the metallic case, and the impact mechanism including an anvil and a hammer configured to apply rotational impact to the anvil.