A method of programming a memory cell of a nonvolatile memory device by executing a plurality of program loops comprises detecting whether a loop count or a level of a program pulse to be applied to the memory cell is within a specific range, wherein the specific range is an operation section in which a level of a current peak flowing into the bitline increases up to a reference value or more, charging a bitline of the memory cell at a first charging speed or a second charging speed slower than the first charging speed according to a result of the detection, and applying the program pulse to a wordline of the memory cell.