This paper’s aim is to provide an insight into when and for what type of innovation are different types of customers most effective participants in the NPD process (Gemser & Perks 2015). Most of prior research has not considered type of innovation or only focused on one stage of NPD process, although both innovation type and each NPD process are critical factors to the NPD performance in the customer co-development context (Chatterji & Fabrizio 2014). Even though some research has examined all stages of NPD process, they also did not specify users or innovation types to compare them. Thus, we will examine the effect of customer participation on NPD performance considering both innovation and user types in terms of each NPD process. The specific research questions are 1) In the NPD process, will the impact of customer participation on NPD performance differ by user-type (lead users vs. ordinary users)? And the NPD stage?, 2) If so, when we consider both user-type and NPD stage, will the impact of customer participation on NPD performance differ depending on the type of innovation (Incremental vs. radical)? The hypotheses are developed as a basis for the subsequent research. This research has several theoretical contributions. First, we discover more appropriate user type in each NPD stage in the customer participation process. Second, we also find more appropriate user characteristics depending on the type of innovation. Third, if lead users are involved rather than ordinary users, customer participation in the development stage can generate positive impact on NPD performance, which is the opposite result compared to previous research (e.g., Chang & Taylor 2016). Finally, we show practical implications and limitations.