A connecting device comprises a first component, a second component which can be connected to the first component by insertion one in the other, and a coupling lever which is mounted movably on the first component and which is adjustable from an open position to a closed position and has coupling elements which cooperate with coupling elements of the first and second components and are designed in such a way that, by an adjusting movement of the coupling lever out of the open position into the closed position, the first and second components can be transferred from a loose state to a fixed state.