A camshaft for activation of the gas exchange valves of an internal combustion engine has two coaxially mounted shafts rotatable inside and with respect to one another, first cams fixedly attached to the first shaft and second cams fixedly attached to the second shaft, a main camshaft drive acting on both shafts, and a device for adjusting the angle of rotation of the first and second shafts with respect to one another by a first actuating drive and adjusting the angle of rotation of both shafts jointly by a second actuating drive. The adjusting device has a rapid response and allows large adjustment angles with a simple structural design.