In processing using a print data processing apparatus that parallelly interprets pages of print data, in the case where a command to reset the number of already interpreted pages is included in the print data, a certain page to be printed is not printed. In the case of detecting a command to invalidate contents interpreted hitherto, an interpreter stores the number of already interpreted pages at the time in point of the detection of the invalidation command in a cache. Then, the interpreter generates intermediate data in the case where the sum of the cached value and the number of already interpreted pages managed by the interpreter coincides with a processing-target page number.