We present the iRing, an intelligent input ring device developed for measuring finger gestures and external input. iRing recognizes rotation, finger bending, and external force via an infrared (IR) reflection sensor that leverages skin characteristics such as reflectance and softness. Furthermore, iRing allows using a push and stroke input method, which is popular in touch displays. The ring design has potential to be used as a wearable controller because its accessory shape is socially acceptable, easy to install, and safe, and iRing does not require extra devices. We present examples of iRing applications and discuss its validity as an inexpensive wearable interface and as a human sensing device.