To provide a roller type input device to be used for a portable information processor such as a portable terminal or a portable telephone set capable of making the input device compacter than a conventional one, and of performing operations such as 'up and down selection', 'right and left selection', and 'decision' without putting a user's finger away from the input device.

In this input device having a cylindridal roller 1 for converting rotational quantity around the shaft of the roller 1 into an electric signal by a rotary encoder 3, and for converting the presence or absence of the upward and downward movement of the roller when the central part of the roller 1 is pushed down into an electric signal by a push switch 5C, a seesaw motion is added to the roller 1. The presence or absence of the clockwise motion of the right edge of the roller 1 is converted into an electric signal by a push switch 5R, and the presence or absence of the anti-clockwise motion of the left edge of the roller 1 is converted into an electric signal by a push switch 5L. The switches 5L and 5R are arranged at the lower part of the roller so that the roller 1 can be made short. Thus, all the operations can be performed only by the roller 1. Therefore, it is not necessary to release a user' finger from the roller, and thereby the operability is improved.