To provide an assisting device capable of generating a large pressure, shearing force or the like on a working part, without dropping it carelessly, and capable of concentrating on work.
A ring 1 or cantilevered member 2 is fixed on both sides of a gripping part of a thumb handle 7. A thumb or an indexing finger is inserted just below the central region of the ring member or the cantilevered member to hook and hold the tool 6. The tool mounting the holding assisting device 5 which has the back of the thumb handle placed from the retinaculum of flexor of the anterior carpal region to the vicinity of the index finger, enables the working part such as a mouth tip to open wide, and both designs to be strongly gripped by using the inside muscles of the front arm.