Innovation and technological progress are crucial to the sustainability of regional economies. Assessing the spatial dimension of the innovation process and evaluating the convergence of regional disparities in technological levels constitute a vital research endeavor. This research is significant because the convergence of economic disparities can be accelerated or impeded depending on the innovation process, specifically whether regional differences in technological levels decrease or increase over time. This chapter provides new insights into regional disparities in total factor productivity (TFP) in Japan using a stochastic convergence model. The model enables the determination of long-term stationarity in the convergence of disparities, a challenge for conventional analyses. First, we assessed the technological level of regional industries by measuring industry-specific TFP. Next, we evaluated the convergence of TFP disparities across regions using the stochastic convergence model. The results indicate that TFP is increasing while regional disparities are narrowing, particularly in the manufacturing sector. Moreover, TFP converged to steady-state levels in each region, highlighting the importance of the regional production environment for innovation. These findings offer important implications for designing strategies to enhance the sustainability of regional economies.