We apply for financial support for the new, fourth phase of the Optical Gravitational Lensing Experiment (OGLE-IV) - one of the largest scale sky surveys worldwide, operating continuously since 1992. During its operation the OGLE project contributed significantly to many fields of modern astrophysics including gravitational microlensing, extrasolar planets searches, stellar astrophysics, Galactic structure and many others. The main scientific goal of the OGLE-IV phase will be the second generation planetary microlensing survey. It should result in top rank discoveries of the Earth mass planets and should provide the full census of planets down to Earth masses orbiting their hosts at 1-5 AU orbits. This parameter space is only accessible to the microlensing technique. Complementary census of planets orbiting at the distances smaller that 1 AU is to be made by space missions using transit technique. OGLE-IV survey will also conduct research in many other top rank astrophysical topics like the search for Pluto size dwarf planets from the Kuiper Belt, search for free-floating black holes, microlensing in the Magellanic Clouds and Galactic disk. Hundreds of new discoveries in the variable star field are also guaranteed. Moreover, OGLE-IV will operate on-line services providing real time photometry of variable objects of many types. The OGLE-IV data will be placed in public domain and available to the astronomical community.