An image rotation method without using a memory includes the steps of: reading, by a JPEG encoder, an input image having mxn macroblocks (wherein ''m'' and ''n'' are natural numbers); rotating image data of the respective macroblocks by a predetermined angle in a predetermined direction when encoding in the JPEG encoder; assigning and inputting a sequence of each rotated image data when encoding in the JPEG encoder; instructing the macroblocks to be output in a sequence changed from an initial input sequence of the macroblocks through use of a program when decoding in a JPEG decoder; and outputting an image rotated by the predetermined angle in the predetermined direction.