Abstract: The mold halves of a blow mold device are mounted on a pair of arms encircling the mold halves in a semicircular arc which arms are latched together by latching means which are located at the parting line of the mold halves at both sides thereof. Due to this structure, merely the portion of the arms extending between said latching means is subjected to bending forces by the blowing pressure. For swinging the arms and actuating the latching means a common slide is provided in parallel relationship to the longitudinal axis of the blow mold, which slide includes a number of control cams which are engaged by cam followers cooperating with said arms and said latching means. The invention provides a compact and light-weight construction allowing to actuate a smaller mass in shorter time, thus increasing the production capacity of the blow mold device.