To provide a mold clamping device of a hollow molding machine which efficiently imparts a mold clamping force and a dwell pressure required for a molding tool to a mold in compliance with the size and shape of the molding tool.

This mold clamping device of a hollow molding machine is constituted of a plurality of tie bars 14, 15 and 16 inserted through an appropriate movable table 13, a forward platen support plate 2, a rear support plate 3 and a pair of platens 4 and 5 with a pair of fitted mutually counter-facing molding tools 6 and 7 and a mold clamping drive mechanism 9 which makes a pair of molding tools perform actions such as the clamping, dwelling and opening of a mold. The forward platen 4 is fitted, in a freely rotating manner, to the upper end part of the forward platen support plate 2, with the help of a leg-shape forward bracket 40 which is hinged to the upper end part and has an upper and a lower support 402. Further, the rear platen 5 is fitted, in a freely rotating manner, to a link arm 91 positioned forward of the mold clamping drive mechanism 9, with the help of a leg-shape rear bracket 50 which is hinged to the link arm 91 and has an upper and a lower support 502.