Individuals residing in more deprived areas have a lower diet quality. While several studies have shown that individuals with a lower diet quality have a higher mortality risk, a low quality diet might also lead to poor health in highly deprived areas. We aimed to examine the association between deprivation within an area and all-cause mortality risk according to diet quality. Methods: We conducted a population-based prospective study on 27994 men and 33273 women aged 45–75 years. Neighborhood deprivation was assessed using the Japanese areal deprivation index (ADI). Dietary intakes were assessed using a validated 147-item food frequency questionnaire. Subsequently, Japanese Food Guide Spinning Top scores were calculated. Hazard ratios (HR) and 95% confidence intervals (CI) of mortality were calculated according to tertiles of ADI by diet quality score. Results: Individuals residing in the most deprived area had the lowest dietary scores. During the 16.7-year follow-up, compared to individuals with a high quality diet residing in the least deprived area, individuals with a low quality diet had a higher risk of mortality according to increment of ADI (P trend = 0.02); the multivariate adjusted HR (95% CI) was 1.07 (1.00-1.15), 1.15 (1.07-1.24), and 1.18 (1.08-1.29) in those residing in the lowest through the highest third of ADI, respectively. However, individuals with a high quality diet had no significant association between ADI and mortality (P trend =0.87). Conclusion: A well-balanced diet may prevent early death associated with neighborhood socioeconomic status among those residing in highly deprived areas.