To provide a hair-cutting auxiliary tool enabling a user having short or angular fingers to cut hair fine by trueing up a regular width of hair easily, without regard to the form of fingers nor the skill of the user.

A first finger sack 1 and a second finger sack 2, both of which are made of a water-proof material, are jointed at a joint part 3 at the root of the fingers almost without gap in the contact surface between the finger sacks 1 and 2 when they are closed. A stopper belt 4 is attached to the joint part 3 for preventing the finger sacks from slipping off.