The mixed alkali metaphosphate glass 12.5Li(2)O-12.5Na(2)O-12.5K(2)O-12.5Cs(2)O-50P(2)O(5) (mol%) compressed under uniaxial stress shows unusually large recovery of its shape during heating above its glass transition temperature (T-g). To clarify the mechanism, the viscous, elastic, and plastic behavior of the metaphosphate glass was investigated with the depth-sensing indentation method. From the load-displacement (P-h) curves of the glass, a large recovery of the depth displacement was found during unloading above T-g. By analyzing the P-h curves with a viscous-elastic-plastic model, the large recovery was concluded to be due to larger elastic deformation than viscous deformation even above T-g. The phenomenon can be attributed to relaxation to the randomly oriented -P-O-P- chain structure from the oriented chain structure formed under stress in the metaphosphate glass.