Experiments are made at the second thermal neutron radiography field (TNRF-2) of the Japan Research Reactor 3M in Japan Atomic Energy Research Institute. Its thermal neutron intensity was 1.5×108 n/cm2/s. The n/γ ratio of the field was 62.5 n/cm2/μSv and so excellent for our purpose. Fig. 5 shows a raw color image obtained at the field. As shown in Fig. 6 objects were an acrylic resin step wedge (left), an iron step wedge (middle) and three kinds of ASTM indicators (right). As the neutron component was dominant, the image was tinged with red. On the other hand an image shown in Fig. 7 was obtained with the last neutron beam shutter was closed. It means the image was composed of gamma component and the tinge of green can be recognized. For our purpose of the simultaneous neutron and gamma ray radiography the neutron dose had to be decreased by inserting an acrylic resin plate. The thickness of 10 mm was experimentally determined for optimum S/N condition.