Abstract: A headwear-size measuring apparatus measures a size of a headwear, an elastic band, or the like and also measures a pressure applied to a wearer's head on wearing the headwear. The headwear-size measuring apparatus includes: a controller; a driving source controlled by the controller; an object extending unit having a diameter size controlled by an operation of the driving source; a pressure measuring unit for measuring an applied pressure of an object and provided at the object extending unit and transmitting the measured value to the controller; an input unit for receiving an established value and transmitting the received value to the controller; a standard data base connected to the controller such that data are transmitted to the controller and storing standard-object sizes and ranges of appropriate pressure applied to a head corresponding to the object sizes; and an output unit for displaying data processed by the controller.