It is important to pre-determine the most suitable exposure factor for obtaining scintigrams by the scinticamera. With use of a scinticamera and the area of interest of a persistenscope, we obtained relationship of X ray film density to cps in the certain area of the image with radioactivity of ^<99m>Tc and ^<196>Au. Then, we determined the exposure time to X ray film on the photoscope III by measuring cps in the above area. Consequently we could pre-determine exposure factor independently from size of the organ, collimators and radio nuclides such as ^<99m>Tc and ^<196>Au.