Electron spin resonance spectroscopy (ESR) measurements of the mechano-radicals produced from ground quartz and quartz glass were studied. Three mechano-radical types were produced : E’center, non-bridging oxygen hole center (NBOHC) and peroxy radical. The ESR spectrum was found to vary with the type of atmosphere during grinding. The concentration of mechano-radicals was approximately proportional to the specific surface area of product. Adjacent E’center and NBOHC radicals recombined with each other. The life time of mechano-radicals was found to be longer than about 3800 h in a vacuum.