Abstract: A fast parallel 2-D discrete casing transform, DCT, device capable of performing a fast 2-D DCT by significantly reducing the number of multiplications during the implementation of the 2-D DCT. N.times.N 2-D input data is re-arranged into N groups so as to be the same as the kernel of a cosine function in order to transform a multiplying form of the cosine function (as the kernel of a 2-D DCT) into a summation form. Then, the first summations and first subtractions are carried out on the re-arranged data, thereby generating first computed data. Then, N 1-D DCT's are carried out on the first computed data. Finally, the 2-D DCT data is generated by carrying out a shifting process after performing additions and subtractions on the 1-D DCT data in log.sub.2 N stages.