Two-dimensional wide-angle neutron diffraction patterns have been measured successfully for uniaxially oriented fully deuterated and fully hydrogeneous polyethylene samples by using an imaging plate system (BIX-3) installed at the Japan Atomic Energy Research Institute. The detailed data analysis allowed us to extract the positions of hydrogen atoms in the crystal lattice accurately. The results were compared quantitatively with those obtained from the X-ray and electron diffraction experiments as well as the computer simulation result.