To provide a constant voltage circuit provided with an overcurrent protection circuit capable of obtaining a short circuit current affected little by fluctuation of a manufacturing process, without increasing the number of circuit elements.

A voltage drop gets large in a resistance R4, when an output current io increases and when an overcurrent protection operation is carried out by the overcurrent protection circuit 4, and a detection voltage V3 gets to a voltage or more provided by adding an offset voltage Vofs to the second partial voltage V2. An NMOS transistor M5 is turned on when brought into this state, and an NMOS transistor M6 is turned off. A drain voltage of the NMOS transistor M5 gets low when the NMOS transistor M5 is turned on, a PMOS transistor M7 is turned on to reduce a gate voltage of the PMOS transistor M7, and a gate voltage of an output transistor M1 is increased to decrease the output current io.

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