To allow a user to make a phone conversation even when the mobile phone and the head of the user are apart by a prescribed distance because it is said that an electromagnetic wave emitted from mobile phones may give an adverse effect on a brain or a heart of people and there are people who dislike the use of the mobile phone mounted on the head.

When a mobile phone is mounted on the auxiliary device of this invention, a speaker of the mobile phone is in close contact with one end of a 1st tube and a microphone of the mobile phone is in close contact with one end of a 2nd tube. Thus, when a user makes a phone conversation by the mobile phone, the user approaches the ear to a truncated cone shaped ear pad at the other end of the 1st tube and the mouth to a truncated cone shaped ear pad at the other end of the 2nd tube so as to allow the user to make the phone conversation even when the mobile phone is apart from the head of the user by a prescribed distance.