It is an experimental report about object contrast according to the Kinds of screen and obtained results as follows : 1. In the same object radiography, use acquired the difference of the object contrast between LT-II ($CaWO_{4};system$) and G4 (Gd system) screens. 2. object contrast more decreased in Gd system screen than $CaWO_{4}$, and object contrast controlled by X-ray tube voltage. 3. The difference of object contrast seen clearly in 80 kVp.