Effects of the excimer laser irradiation on regenerated cellulose fibers were investigated. The surface structure change was remarkable only when the ArF laser was applied. Small pores and fibrils were observed on the fiber surface at the high fluence irradiation. In some cases, several cracks were observed inside the fiber. The fiber structure change was strongly dependent on fluence and number of pulses. XPS analysis indicated an increase of carbonyl groups and removal of CO and CO2 on the fiber surface. Concerning the fiber properties, the tensile strength lowered, and the moisture content was improved a little. Those property changes could be explained by the breakage of intermolecular hydrogen bonding and that of the main chain of the cellulose molecule. Increase of specific surface area and chemical structure change suggest that irradiated fiber can be applied as a component for soft composite materials.