PURPOSE: To obtain a semiconductor memory which can accurately write data of analog quantity with simple constitution.

CONSTITUTION: Sources of memory cells A11-C1n, C21-C2n are grounded through a resistor RW, input data Ain is impressed to drains. Storage voltage VW is applied to control gates 25 of each memory cells C11-C1n, C21-C2n. And electric charges stored in floating gates 24 of each memory cells C11-C1n, C21-C2n are extracted toward the control gates 25, when a potential difference ΔV between a potential of the control gate 25 and a potential of the floating gate 24 is made the prescribed value, each memory cells C11-C1n, C21-C2n are turned off, and extraction of electric charges is stopped.