A memory device includes stacked word lines stacked and a semiconductor channel passing through the word lines in a first direction. Memory cells are disposed along the semiconductor channel in the first direction. Each memory cell includes a charge retention film between the semiconductor channel and a respective word line in the plurality of word lines. A controller is connected to the semiconductor channel and the word lines and configured to apply a program voltage during a program operation to a memory cell at a potential that increases in voltage steps, and a voltage increment between the voltage steps decreases during the program operation. The increment voltage is changed by the controller depending on a position of the memory cell along the semiconductor channel in the first direction.