Provided herein may be a memory device capable of completing program operations for multiple pages in one ready/busy period. The memory device may include a plurality of memory cells configured to form a plurality of pages, a peripheral circuit configured to perform a first program operation and a second program operation and control logic configured to control the peripheral circuit to receive least significant bit (LSB) page data of a page adjacent to a selected page, center significant bit (CSB) page data, and most significant bit (MSB) page data of the selected page from a memory controller, and program the LSB page data of the page adjacent to the page adjacent to the selected page and to obtain LSB page data from the selected page, previously stored in the selected page, and program the LSB page data, the CSB page data and the MSB page data of the selected page to the selected page.