To provide a dial and its knob for rotating encoder data entry to give them rapid spinning with fingertips, fine tune the dial with a minute rotation angle and perform data input for coarse tuning and fine tuning.

A knob part is formed by a cusped part for a thin rod 1-1 shaped like the thin rod and a thick neck part 1-2 shaped like a thick column thicker than the cusped part for the thin rod 1-1. The dial can go into approximately five revolutions with one twist in spinning the cusped part 1-1 by taking it between balls of fingers like twisting paper into a string or topping a spin with its spindle. The data input for the coarse tuning can be therefore performed at high speed by spinning the cusped part 1-1 by taking it between the balls of the fingers, the rotation with a minute angle can be given to the thick neck part 1-2 by setting a diameter of the thick neck part 1-2 several times as large as the cusped part 1-1, and the data input for the fine tuning can be performed with sufficient accuracy.