In order to obtain a ribbon feeding shaft capable of accurately adjusting a position of a regulating member and preventing a positional deviation, a long sheet material holding device includes a pair of first locking groove trains (91c and 91d) arranged in parallel with each other along the axial direction of the holding shaft (91), the pair of first locking groove trains (91c and 91d) having a series of grooves (61c and 61d) respectively, the series of grooves (61c and 61d) extending across the axial direction of the holding shaft (91), each of the series of grooves (61c and 61d) being provided with slope surfaces (71c, 71d) sloped along the axial direction of the holding shaft (91) and oppositely to each other and perpendicular surfaces (81c, 81d) perpendicular to the axial direction of the holding shaft (91), and a pair of second locking groove trains (92c, 92d) formed in a pair of locking members (92x, 92y) provided in the regulating member 92 inserted into the holding shaft (91), to match the surfaces of the pair of first locking groove trains (91c and 91d).