The present invention relates to a hinge module of a foldable type device, which is connected to two casings for being relatively rotated for being in a folded status or in a unfolded status, each of the casings has a fixed outer casing and a moveable inner casing. The hinge module includes a base and two slide mechanisms. One end of a connection rod of each slide mechanism and one end of the linkage member are respectively pivoted to two pivotal parts at one end of the base; after each inner casing is driven to reversely displace, one end of each plate member is separated from each block part, so as to reversely swing and shift for forming an accommodation space allowing a bent central portion of a flexible monitor to be accommodated.