Disclosed is an electrostatic discharge protection circuit capable of realizing speeding up of differential signals by reducing a capacitance of the circuit. Transmission lines are connected to an IN terminal and an IN Bar terminal and differential signals are input to the terminals. The ESD protection circuit is connected to the transmission lines and protects an internal circuit from a surge voltage applied to the IN terminal and the IN Bar terminal. A pair of transistors of the ESD protection circuit is formed in the same well. Thereby, when differential signals transit, charges in drains of the pair of transistors holding a state before a transition transfer in the same well. As a result, the capacitances in the drains of the pair of transistors are reduced with respect to the transition of differential signals so that the speeding up of differential signals can be realized.