To provide a highly-productive product stacking device applicable to a sheet material, such as a photo paper and a poultice, that is difficult to automatically collect and stack to count and pack the predetermined number of sheets.

In a long sheet processing line having a web feeding device and a sheet processing device for processing a long sheet continuously delivered from the web feeding device, the product stacking device stacks products processed by the sheet processing device. At least two sets of the product stacking devices are provided so that the product stacking devices are switched and alternately used each time the predetermined number of products are stacked.