A semiconductor device includes: a voltage regulator generating, based on a power supply voltage, an internal power supply voltage having a voltage value lower than that of the power supply voltage and to apply the internal power supply voltage to a power supply line; an internal circuit receiving the internal power supply voltage via the power supply line and a grounding line; and a protection circuit in which first to n-th transistors of PNP type which are Darlington-connected. A collector terminal of each of the first to the n-th transistors is connected to the grounding line. An emitter terminal of the first transistor within the first to the n-th transistors is connected to the power supply line while a base terminal of the n-th transistor within the first to the n-th transistors is connected to the grounding line.