In a glass product forming machine having molds 1A and 1B each composed of a pair of split molds 11 and 12, and a mold cooling device X for cooling the molds 1A and 1B to control the temperatures thereof, in order to prevent the occurrence of a defect such as deformation or cracks in a formed article due to a temperature difference between the split molds 11 and 12, the mold cooling device X is configured to include: cooling mechanisms 3R and 3L provided to the respective split molds, the cooling mechanisms each individually applying cooling air to each of the split molds 11 and 12 of the molds 1A and 1B; valve mechanisms 30R and 30L for individually opening and closing each of paths for introducing cooling air to the respective cooling mechanisms 3R and 3L; temperature detection means for detecting the temperature of at least one of the split molds; and a temperature control device 9 for generating and outputting control signals for controlling the opening and closing operations of the respective valve mechanisms 30R and 30L on the basis of the detected temperature value by the temperature detection means.