A method and a device for performing communication by using a non-orthogonal code multiple access scheme in a wireless communication system are provided. Particularly, a terminal receives control information from a base station. The terminal modulates or demodulates a terminal-specific NCC on the basis of the control information. The terminal performs the non-orthogonal code multiple access scheme by using the terminal-specific NCC. The control information includes information on a codeword composed of a Grassmannian sequence. The codeword is included in a codebook predefined for the non-orthogonal code multiple access scheme. Each coefficient of the Grassmannian sequence is quantized on the basis of an M-quadrature amplitude modulation (M-QAM) constellation.