To diversify the research stream on the exterior technology collaboration network of small and medium enterprises (SMEs), this research has analyzed the impacts of SMEs’ productivity improvement and their chief executive officer-driven technology development on the relation between their exterior technology collaboration network heterogeneity and cost reduction from technology development. Through ordinary least squares regression by using the 2,200 data of the SMEs in South Korea, this research has resulted in the following fresh findings. First, the positive effect of SMEs’ exterior technology collaboration network heterogeneity on the cost reduction from technology development is partially mediated by their productivity improvement from technology development. Second, the positive effect of the exterior technology collaboration network heterogeneity is moderated by the chief executive officer-driven technology development. Third, the partial mediating effect of the productivity improvement from technology development exists when the chief executive officers drive the technology development.