In this study, a comparative study was carried out to investigate the direct and indirect impacts of fuzzy front end (FFE) activities and changes in project execution on new product development (NPD) projects success of business-to-business type (B2B) and business-to-consumer type (B2C) projects respectively in Japanese manufacturing firms. Structural equation modeling (SEM) analysis was used to analyse the data. The following conclusions were obtained from analysis results. The ideal activities during the FFE and the project execution were changed according to the situation such as product and period. Following contingency theory, managers should adapt to external and internal circumstances. Results revealed that problems were found in the B2B and B2C respectively. B2B projects should intensify the reduction of market uncertainty and changes in the project execution phase were kept to minimum. B2C projects should activate the reduction of technical uncertainty and made the project execution phase flexible. In further studied, it seems beneficial to analyse the data another perspective such as company size or industry. It can offer more practical result and be applied for real business. These results contribute to NPD project management according to types of the products of firms.