A driving force transmission apparatus includes: a front housing and an inner shaft coaxially with each other and rotatable relative to each other; a main clutch transmitting torque between the front housing and the inner shaft; and a cam mechanism having a main cam and a pilot cam and using the main cam to press the main clutch. Where a circumferential gap angle between each spline tooth of the front housing and a corresponding first protrusion of outer clutch plates is θ1, a circumferential gap angle between each spline tooth of the inner shaft and a corresponding protrusion of inner clutch plates is θ2 and a circumferential gap angle between each spline tooth of the inner shaft and a corresponding protrusion of the main cam is θ3, the inequality θ1+θ2−θ3≧1.0° is satisfied.