In the standard model of GRBs, protons can be accelerated as well as electrons. Through the photomeson reaction, such protons can produce high energy neutrinos, which may be detected by large Cherenkov detectors such as IceCube. We have carried a systematic and much more thorough calculation than past work analyses of this neutrino emission to determine the high energy neutrino background from GRBs. By executing the Monte Carlo simulation kit Geant4, we can take account of pion-multiplicity and proton-inelasticity, and investigate those effects. We also find that the obtained neutrino background can be comparable with the prediction of Waxman & Bahcall without supposing the enough large nonthermal baryon loading factor necessary for the assumption that GRBs are the main sources of UHECRs. We will discuss the constraints on the nonthermal baryon-loading factor and the effects of magnetic fields.