A protective circuit (301) and a display drive device. The protective circuit (301) comprises: when an electrical overstress problem occurs in a logic signal, the voltage of an output end of a controlled switch circuit (100) is greater than a first preset voltage, so that a voltage threshold circuit (101) is turned on, and the controlled switch circuit (100) turns off an input end and the output end thereof, thereby preventing electrical overstress from affecting a driver chip (300) and causing damage to the driver chip (300). Moreover, the voltage potential of a controlled end of the controlled switch circuit (100) is clamped by means of a voltage clamp circuit (102) to stabilize the operating characteristics of the controlled switch circuit (100).