Disclosed are a program method and a nonvolatile memory device. The method includes receiving program data to be programmed in memory cells; reading the memory cells to judge an erase state and at least one program state; performing a state read operation in which the at least one program state is read using a plurality of state read voltages; and programming the program data in the memory cells using a plurality of verification voltages having different levels according to a result of the state read operation. Also disclosed are methods using a plurality of verification voltages selected based on factors which may affect a threshold voltage shift or other characteristic representing the data of a memory cell after programming.