A nonvolatile memory device includes a memory cell array and a read/write circuit connected to the memory cell array through bit lines. The read method of the nonvolatile memory device includes receiving a security read request, receiving security information, and executing a security read operation in response to the security read request. The security read operation includes reading of security data from the memory cell array using the read/write circuit, storing of the read security data in a register, performing security decoding on the read security data stored in the register using the received security information, resetting the read/write circuit, and outputting a result of the security decoding.