Abstract
Since the X-ray sources in the central region of M82 are crowded, a high spatial resolution instrument like the Chandra X-ray Observatory is needed to resolve the images. M82 has been observed 13 times between 1999 and 2007 with Chandra; some of them were designed to observe M82 X-1 with special configurations. To study the long-term variability of the whole galaxy, we used nine Chandra data sets with relatively long exposure time and large field of view from the Chandra Data Archive.