An apparatus and a method for securing a communication information in a CDMA communication system are disclosed. The method of the invention comprises the steps of encoding a input analog signal as an information bit having a predetermined size and generating a vocoder packet information bit, and encrypting said encoded vocoder packet information bit using a block cipher and a security key, and adding a frame quality indicator and the encoder tail bits to the encrypted vocoder packet information bit and configuring it as a CDMA frame, and transmitting the CDMA frame which passes a convolutional encoder, interleaver, and modulator in sequence, to a base station through an assigned frequency band. Further, The method of the invention comprises the steps of receiving a signal from a base station, and reproducing it as a CDMA frame, and extracting an encrypted vocoder packet information bit from the reproduced CDMA frame, and decrypting the encrypted vocoder packet information bit by a block cipher and a security key, and decoding the decrypted vocoder packet information bit.