In this study, we propose a three-dimensional interface using a wire. This interface obtains a three-dimensional position by the length and direction of the wire. The length of the wire is measured by a rotary encoder, and the direction of the wire is measured by two linear image sensors that do not come into contact with the wire. An analog signal from the linear image sensor is sent to a PC through an analog comparator. The three-dimensional position of the wire tip can be obtained by these devices at high speed and low cost.