A radiation image read-out apparatus comprises a linear stimulating ray source for emitting stimulating rays to a linear portion of a stimulable phosphor sheet carrying a radiation image stored therein, and a line sensor constituted by many solid state photoelectric conversion devices. The line sensor extends at least over the length of the linear portion of the stimulable phosphor sheet exposed to stimulating rays. Light emitted by the linear portion of the stimulable phosphor sheet upon stimulation thereof is received and photoelectrically converted by the solid state photoelectric conversion devices. The portion exposed linearly to stimulating rays and the line sensor are moved with respect to the stimulable phosphor sheet, and outputs of the line sensor are sequentially read out in accordance with the movement of the portion exposed linearly to stimulating rays and the line sensor with respect to the stimulable phosphor sheet.