The detection of a single spin is demanded for variety of applications, e.g., for reading and manipulation of isolated spins for spintronics and quantum computation. We are developing instrumentation of the detection of a single spin using scanning tunneling microscope (STM). Especially, a method that detects the Larmor precession by monitoring a variation of tunneling current, called ESR-STM, has a large advantage due to its compatibility with solid devices and atom-scale spatial resolution. We successfully developed ESR-STM instrument which can detect the single spin in SiO layers. In addition, for the realization of the molecular-spintronics, single molecule magnet (SMM) is one of the most promising material. We investigated the spin of SMM by detecting Kondo states. We found that the Kondo peak intensity shows a clear variation with the conformational change of the molecule; namely the azimuthal rotational angle of the Pc planes.