Objective: Improvements in diet can decrease the cancer rates. The aim of the present study was to determine the relationships between self-perception of diet quality and personality, impulsiveness, stress, coping strategy, sense of coherence, self-efficacy, and social support. Methods: This cross-sectional study was conducted using a multiple-stratified random sampling method based on the Korea Census of 2007. In October 2009, investigators conducted 15-minute face-to-face interviews with 1,530 South Korean volunteers who ranged from 30 to 69 years of age without a history of cancer. Results: Respondents were more likely to perceive that they consumed a healthy diet if they were older than 50 years, lived with a partner, had a monthly family income greater than $4,000 USD, had a low perceived risk of cancer, consumed less alcohol, exercised regularly, had a less agreeable or conscientious personality, had low stress levels, had a high sense of coherence or self-efficacy, and had ample social support. Conclusion: Psychosocial factors, such as personality, stress, sense of coherence, self-efficacy, and social support, are associated with the self-perception of diet quality. Analysis of the factors that contribute to a perceived healthy diet could assist with the design of educational campaigns.