PROBLEM TO BE SOLVED: To provide a low cost adsorption device capable of adsorbing a recording medium stably regardless of the size of the recording medium, and an image forming device.SOLUTION: A conveyance guide member 8 having a plurality of conveyance ribs has: an air outlet for blowing out an air flow blown out from blower means to a surface where the conveyance ribs are formed; an air flow guide part 7 for reducing a flow passage area of the air flow on a further upstream side than the air outlet, and changing the direction of the air flow blown out from the air outlet so as to go toward a width direction end part of the recording medium; and a vent hole 4 formed at the plurality of conveyance ribs. By using a negative pressure generating by the flow passage area of the air flow generated by the blower means becoming narrower by a fluid guide part, the recording medium is drawn to the conveyance guide member side and adsorbed to the conveyance ribs.
