In this paper, a method based on second order sliding mode control(2-SMC) is developed to design a nonlinear controller for a quadcopter vehicle subjected to disturbance in the z-axis. The controller is divided into two subcontrollers, one for the fully actuated degrees of freedom and the other one for underactuated degrees of freedom. Nonholonomic constraints governing the relation between underactuated subsystem are developed. Stability of the proposed controller is guaranteed in Lyapunov sense and different simulations are carried out to present the performance characteristics of the system. The chattering effect is highlighted and tackled.