An ultrasonic transmission member including one end part and the other end part and transmitting an ultrasonic wave input into the one end part to the other end part is formed by preparing a main mold having a casting cavity corresponding to a whole outer shape of the ultrasonic transmission member, melting an alloy which is a material of a metallic glass, and pouring the melted alloy into the casting cavity of the main mold to solidify the melted alloy in a liquid phase state thereof.
