Palmoplantar pustulosis (PPP) is a chronic dermatitis characterized by sterile intra-epidermal pustules associated with erythema and scales on the palms and soles. Tumor necrosis factor (TNF)-α/interleukin (IL)-23/IL-17 inflammatory pathway may be involved in the pathogenesis of PPP, and the skin lesions manifest the enhanced expression of IL-8 in keratinocytes and increased levels of antimicrobial peptide cathelicidin, leucine leucine-37 in vesicles/pustules. Some PPP patients are associated with arthro-osteitis, called pustulotic arthro-osteitis (PAO). Dietary habits may modulate the pathogenesis of PPP, however, have not been investigated in PPP patients. We evaluated dietary habits in adult Japanese PPP patients, using a validated, brief-type self-administered diet history questionnaire, and compared their results to those of age- and sex-matched healthy controls. The results in PPP patients with PAO were compared to those in the patients without. Japanese PPP patients showed higher body mass indices (BMIs), higher intakes of pulses and sugar/sweeteners, and lower intake of vitamin A, compared to those of healthy controls. The bivariate and multivariable logistic regression analysis showed that PPP was associated with high BMI, high intake of pulses, and low intake of vitamin A. The sodium intake and BMI were positively correlated with palmoplantar pustulosis area and severity index (PPPASI). The linear multivariate regression analysis revealed that sodium intake and BMI were predictors of PPPASI. The age and sodium intake in the patients with PAO were lower than those in the patients without. The bivariate and multivariable logistic regression analysis showed that PAO was negatively associated with age and sodium intake. This is the first study showing the dietary habits in patients with PPP. Further studies should clarify if the dietary intervention to correct the BMI and sodium intake will alter the progress of PPP.