The silico-sillenite single crystals with various concentration of impurity iron ions have been studied. An effect of light on the charge state of iron ions has been found involving the transition of Fe3+ to Fe2+. The transition was recorded by means of ESR signal intensity measurement. The parameters of the ESR absorption lines were obtained and analyzed. The nature of chemical bonds between iron ions and surrounding ligands was shown to be changed by the laser-induced recharge. A consistent model for optical recharge process and magnetic properties modification of iron impurity centers in the silico-sillenite single crystals has been suggested.