An image signal processing apparatus and a method thereof which can simplify design of a circuit for controlling each of camera modules when a terminal has two camera modules therein, the image signal processing apparatus includes: first and second camera modules for capturing a subject; a digital signal processor for controlling each operation of the first and second camera modules and processing image signals captured by the first and the second camera modules; and a switch module for supplying control signals inputted through the digital signal processor to the first and second camera modules, and selectively outputting the image signals captured by the first and second camera modules to the digital signal processor.