Current instrumentation activities and the open user status of Okayama Astrophysical Observatory (OAO) are reviewed. There are two telescopes in operation and one telescope under reforming at OAO. The 188cm telescope is provided for open use for more than 200 nights in a year. The typical over-subscription rate of observation proposals for the 188cm telescope is ${~}$ 1.5 - 2. The 50cm telescope is dedicated to $gamma$-ray burst optical follow-up observation and is operated in collaboration with Tokyo Institute of Technology. The 91cm telescope will become a new very wide field near-infrared camera in two years. The high-dispersion echelle spectrograph (HIDES) is the current primary instrument for the open use of the 188cm telescope. Two new instruments, an infrared multi-purpose camera (ISLE) and an optical low-dispersion spectrograph (KOOLS), are now under development. They will be open as common use instruments in 2006.