The invention relates generally to a multi-chip package (MCP) memory device, and more particularly, but without limitation, to a MCP memory device having a reduced size. In one embodiment, the MCP memory device includes: a transfer memory chip; and a plurality of memory chips coupled to the transfer memory chip, each of the plurality of memory chips including an internal voltage generating circuit, the transfer memory chip configured to receive a plurality of command signals from outside the MCP memory device, the transfer memory chip further configured to output a plurality of control signals to the plurality of memory chips based on the plurality of command signals. Embodiments of the invention also relate to a method of controlling an internal voltage of the MCP memory device.