Urban green spaces (UGS) are essential for urban residents because they are a source of ecosystem services. This study explored the quality and quantity of UGS and their impacts on residents’ life satisfaction in the case of a mature society in the Tokyo metropolitan area. The quantity of UGS was measured by remote-sensing, whereas its quality was measured using 46,076 responses to our questionnaire. Concerning quality, the type and number of UGS problems perceived by residents were employed as indices. Specifically, respondents responded to some questionnaire items asking them about what kind of problems they experience with their neighborhood UGS. The regression results empirically show that residents who perceive more problems with their neighborhood UGS have less life satisfaction; e.g., obstructing their recreational usage of UGS appears to notably decrease life satisfaction. The regression results using the cross-term for quality and quantity show that an increase in UGS worsens rather than improves life satisfaction when people perceive a certain number of problems with their UGS. These results emphasize the importance of focusing not only on quantity of UGS, but also on their quality, especially in recreational factors, when considering urban management.