Image decoding apparatus and image decoding method

An image decoding apparatus, a semiconductor device, and a image decoding method are provided, capable of reducing the apparatus size and reducing the maximum value of current consumption, when simultaneously outputting a multi-channel digital images. A multiplexing processing portion 23 of the image decoding apparatus outputs a multiplexed data B1 obtained by time division multiplexing of the image data A1 to A3 stored in each memory 22 after output from the multi-channel image decoding portion 10 and a phase output signal C2 which indicates a phase of any one of image data among multiplexed image data A1 to A3. A synthesizing output processing portion 24 generates and outputs synthesized image data B2 for displaying more than two image data among image data A1 to A3 on one image screen. A selection output portion 25 outputs any one of the input multiplexed image data B1, the synthesized image data B2, and any one of image data A1 to A3 as a digital image data.