A yarn winder comprising: a bobbin holder which extends in a predetermined longitudinal direction, bobbins on which yarns are wound, respectively, being attached to the bobbin holder to be lined up in the longitudinal direction; a traverse unit which is configured to traverse the yarns; a contact roller which extends in the longitudinal direction and is configured to apply a contact pressure to packages which are formed by winding, onto the bobbins, the yarns having been traversed by the traverse unit; and a roller supporting member which supports the contact roller to be rotatable, the roller supporting member including: supporting portions which rotatably support at least end portions in the longitudinal direction of the contact roller and extend at least radially outward from a radial central portion of the contact roller; and a rigidity improving member which extends in the longitudinal direction and to which the supporting portions are fixed, the rigidity improving member being provided so as not to overlap the bobbin holder and the traverse unit when viewed in the longitudinal direction, and when viewed in the longitudinal direction, the rigidity improving member having a part which is longer than each of the supporting portions in a direction orthogonal to the direction in which the supporting portions extend, wherein the yarn winder further comprises a frame which extends in the longitudinal direction and supports the roller supporting member, characterized in that a cross section of at least a part in the longitudinal direction of the rigidity improving member, which is taken along a direction orthogonal to the longitudinal direction, at least partially surrounds a cross section of the frame taken along the direction orthogonal to the longitudinal direction. a bobbin holder which extends in a predetermined longitudinal direction, bobbins on which yarns are wound, respectively, being attached to the bobbin holder to be lined up in the longitudinal direction; a traverse unit which is configured to traverse the yarns; a contact roller which extends in the longitudinal direction and is configured to apply a contact pressure to packages which are formed by winding, onto the bobbins, the yarns having been traversed by the traverse unit; and a roller supporting member which supports the contact roller to be rotatable, the roller supporting member including: supporting portions which rotatably support at least end portions in the longitudinal direction of the contact roller and extend at least radially outward from a radial central portion of the contact roller; and a rigidity improving member which extends in the longitudinal direction and to which the supporting portions are fixed, the rigidity improving member being provided so as not to overlap the bobbin holder and the traverse unit when viewed in the longitudinal direction, and when viewed in the longitudinal direction, the rigidity improving member having a part which is longer than each of the supporting portions in a direction orthogonal to the direction in which the supporting portions extend, wherein the yarn winder further comprises a frame which extends in the longitudinal direction and supports the roller supporting member, characterized in that a cross section of at least a part in the longitudinal direction of the rigidity improving member, which is taken along a direction orthogonal to the longitudinal direction, at least partially surrounds a cross section of the frame taken along the direction orthogonal to the longitudinal direction. supporting portions which rotatably support at least end portions in the longitudinal direction of the contact roller and extend at least radially outward from a radial central portion of the contact roller; and a rigidity improving member which extends in the longitudinal direction and to which the supporting portions are fixed, the rigidity improving member being provided so as not to overlap the bobbin holder and the traverse unit when viewed in the longitudinal direction, and when viewed in the longitudinal direction, the rigidity improving member having a part which is longer than each of the supporting portions in a direction orthogonal to the direction in which the supporting portions extend, wherein the yarn winder further comprises a frame which extends in the longitudinal direction and supports the roller supporting member, characterized in that a cross section of at least a part in the longitudinal direction of the rigidity improving member, which is taken along a direction orthogonal to the longitudinal direction, at least partially surrounds a cross section of the frame taken along the direction orthogonal to the longitudinal direction.