Disclosed herein is a spacer fixing structure including a core member constituting a core to be wound with a coil; and a plate spacer fixed to the core member. The spacer has a loop shape. A communication groove is formed in at least one surface of front and back surfaces of the spacer, and extends radially to communicate with inner and outer peripheries of the spacer. A region of the at least one surface of the spacer other than a grooved portion is left as a flat surface. At least the flat surface of the spacer is adhered to the core member via an adhesive layer made of an adhesive.