Force sensing in nano-scale can be realized by using nanoparticles of “elastico-luminescence” (a new inorganic material which emits light in response to externally applied mechanical stress in elastic region). By applying the material as a coating on the surface of subject, a technology for two-dimensional visualization of stress distribution has been innovated. In order to characterize the stress-induced luminescence from a single particle, we have developed an evaluation equipment utilizing an atomic force microscope (AFM) and photon counting system, and have succeeded in capturing the stress-induced luminescence from a single nanoparticle. The luminescence intensity increases with the increasing force on the nanoparticle, demonstrating that elastico-luminescence nanoparticle can act as force/strain sensor in nanometer region. A force sensor with a diameter of 20 nm has been developed.