An operating method of a nonvolatile memory device includes receiving, at the nonvolatile memory device, a suspend command, suspending, at the nonvolatile memory device, a program operation being performed, in response to the suspend command, receiving, at the nonvolatile memory device, a resume command, and resuming, at the nonvolatile memory device, the suspended program operation in response to the resume command. The program operation includes program loops, each of which includes a bit line setup interval, a program interval, and a verify interval. In the program interval of each of the program loops, a level of a program voltage to be applied to selected memory cells of the nonvolatile memory device increases as much as a first voltage. A difference between a level of the program voltage finally applied s suspend and a level of the program voltage applied first after resume is different from the first voltage.