Electrostatic protection circuit and semiconductor integrated circuit apparatus

An electrostatic protection circuit that is connected via a first node to a first terminal to which a first potential is supplied, and is connected via a second node to a second terminal to which a second potential lower than the first potential is supplied, the electrostatic protection circuit comprising:

• a first impedance element, one end thereof being connected to one of the first node and the second node, and the other end thereof being connected to a third node;
• a capacitor, one end thereof being connected to the third node, and the other end thereof being connected to the other of the first node and the second node;
• a first transistor that is connected between the one of the first node and the second node and a fourth node, and is placed in an electrically conductive state in accordance with an increase in voltage generated at both ends of the first impedance element;
• a voltage divider circuit that includes a second impedance element and a third impedance element and divides voltage between the other of the first node and the second node and the fourth node, the second impedance element being connected between the fourth node and a fifth node, and the third impedance element being connected between the other of the first node and the second node and the fifth node;
• a second transistor that is placed in an electrically conductive state in accordance with an increase in voltage generated at both ends of the third impedance element;
• a detection circuit that activates an output signal upon detection of the electrically conductive state of the second transistor;
• and
• a discharge circuit that is connected between the first node and the second node, and allows current to flow from the first node to the second node when the output signal of the detection circuit is activated.