A photosensor substrate includes: a substrate 31; gate lines arranged on the substrate 31 and extend in a first direction; source lines Si arranged on the substrate 31 and extend in a second direction; transistors arranged in correspondence to points of intersection between the source lines and the gate lines, respectively, and are connected therewith; an insulating layer that covers the transistors; photoelectric conversion elements 4 arranged in correspondence to the points of intersection between the source lines and the gate lines, and are connected with the transistors via first contact holes CH3 in the insulating layer, and bias lines 8 that extend in the second direction, and are connected with the photoelectric conversion elements 4. The source lines are connected with the transistors via second contact holes CH2 in the insulating layer, and have a line width greater than a line width of the bias lines 8.