We investigated effects of collaboration and characteristics of collaborative cognitive processes in creative problem solving through the protocol analysis. In our experiments, subjects were assigned to a single or pair condition, and required to generate ideas of new playground equipments. We analyzed the verbal protocols on the basis of the Geneplore model as a model of creative problem solving processes, which was suggested by Finke, Ward, & Smith (1992). The experimental results showed that (1) about effects of collaboration, the pair subjects generated higher scored ideas from the viewpoint of originality than the single subjects, (2) about characteristics of collaborative cognitive processes, the pair subjects developed, generally speaking, more actively explanation and evaluation behaviors about their ideas than the single subjects and (3) focusing on subjects' sequences of generating ideas, they added and modified their ideas more actively, and (4) the higher scored pairs in the pair condition unified and reconstructed their ideas more aggressively than the lower scored pairs.