An X-ray transmissive substrate is etched to form a plurality of grooves, a plurality of X-ray transmitting sections, and a plurality of supporting portions. The grooves, formed between the X-ray transmitting sections, extend in Y direction and are arranged in X direction orthogonal to the Y direction. In the grooves, the supporting portions protrude from sides of the X-ray transmitting sections in the X direction and are arranged alternately in the Y direction. The supporting portions support the X-ray transmitting sections when the grooves are filled with an X-ray absorbing material through electroplating. The supporting portions prevent the X-ray transmitting sections from falling over due to waves of a plating liquid and uneven growth of the X-ray absorbing material.