A radiation image photographing apparatus is provided with a bias source to apply a bias voltage via bias lines to radiation detecting elements arranged in a two dimensional form in regions divided by scanning lines and signal lines. The bias lines are connected to the radiation detecting elements with a ratio of one bias line to the radiation detecting elements arranged on one column in an extension direction of the signal line, and the bias lines are connected per a predetermined number of bias lines to either one of a plurality of connection lines. The bias voltage is applied from the bias source to the connection lines via the bias lines so that the bias voltage is applied to the radiation detecting elements via the bias lines connected to the connection lines.