Scattered-rays are produced from objects in x-ray diagnosis and the quality of x-ray image is influenced by presence of the scattered-ray. Therefore, constant ways and means to suppress and to eliminate the scattered-ray were devised. Authors made an experimental study on the scattered-ray content in transmitted-ray using acryl phantoms and obtained the results as follows: 1. The scattered-ray content in transmitted-ray is not influenced by filtration and tube voltage. 2. Irradiated field size and the thickness of object are a potent influence to scattered-ray content.