Crystalline silicon particles of nanometer order usable as a semiconductor element are provided by a method for producing SiOx particles, comprising irradiating SiOx (X is 0.5 or more and less than 2.0) particles each including therein an amorphous silicon particle having a particle diameter of 0.5 to 5 nm with light, and preferably a laser beam, to produce SiOx (X is 0.5 or more and less than 2.0) particles each including therein a crystalline silicon particle having a particle diameter of 1 to 10 nm.