A driving force transmission device includes an input section and an output section with rotation axes nonparallel to each other to avoid backlash. A driving force transmission device (1) includes a first rotator (2), a second rotator (3), and spheres (5A, 5B, 5C). The first rotator (2) performs one of an input operation and an output operation of a driving force and includes a concave surface (7). The second rotator (3) performs the other of the input operation and the output operation of the driving force and includes a convex surface (13) fitted into the concave surface (7). The spheres (5A, 5B, 5C) are between the concave surface (7) and the convex surface (13). The concave surface (7) has holes (32A, 32B, 32C) in which the respective spheres (5A, 5B, 5C) are received. The convex (13) surface has a groove (29, 30) that receives parts of the spheres (5A, 5B, 5C) protruding from the holes (32A, 32B, 32C).