PURPOSE: To make a constant voltage source circuit in which temperature dependency is eliminated from output voltage.

CONSTITUTION: A PMOS transistor 42 is provided between a constant current source 40 composed of a resistor 41 and a constant voltage source 43 composed by serially connecting plural NMOS transistors 44. The gate of the PMOS transistor is connected with an output VOUT. When the output voltage of the constant voltage source 43 rises due to temperature changes, the current flowing in the constant voltage source 43 decreases because the ON resistance of the PMOS transistor 42 rises with this. Thus, as the output voltage of the constant voltage source 43 is pressed in the lowering direction, the output of constant voltage to the VOUT is always held constant regardless of temperature changes.