To provide a small-sized cord binder not becoming an obstacle even if set to a cord, capable of easily binding the round bundled cord such as a microphone cord or the like and being easily released when the cord is used.

This invention relates to a binder for use in binding a connection cord attached to acoustic equipment such as a microphone and electric machine units and the like characterized in that the binder comprises a binding hook (1) and a binding band (2) inserted into the binding hook to fix the cord, the binding hook (1) is provided with an engagement part (5) for use in engaging with grooves (slits) of the binding band (2) at its upper part and the binding band (2) has some grooves (slits) properly spaced apart from one another in band shapes having extending and retracting elasticity.