The present invention discloses an input buffer circuit capable of recognizing and driving a low-voltage signal, output from a low-voltage environment, in a high-voltage environment and a gate driver IC including the input buffer circuit. The input buffer circuit is configured to include two or more multi-stage inverters and to recognize and output a gate signal having a different voltage domain from an operating voltage. Accordingly, a signal interface environment between chips operating in different voltage domains can be provided.