Purpose <p>Although kleptomania is frequently observed in patients with eating disorders, research on its causes is scarce, and no scale exists to assess it. This pilot study was done to develop such a scale and to evaluate its validity and reliability.</p> Methods <p>Forty-six female patients with anorexia nervosa incarcerated at the Kitakyushu Medical Prison completed our newly developed questionnaire that is based on the DSM-5 diagnostic criteria for kleptomania. All participants had developed an eating disorder prior to their initial incarceration in a correctional facility, had no history of stimulant abuse, and were incarcerated for theft.</p> Results <p>Factor analysis (principal axis method, Promax rotation) identified three significant factors: “Elation/Pleasure”, “Material/Monetary Desire”, and “Impulsivity.” The test–retest correlation coefficients for each item were generally high, confirming test–retest reliability. While the Cronbach’s alpha coefficients for items with high factor loadings on each factor were moderate, the correlations between factors were low, suggesting that each factor represents an independent construct. The “Elation/Pleasure” factor aligned with DSM diagnostic criteria B and C, the “Impulsivity” factor aligned with Criterion A, and the “Material/Monetary Desire” factor contradicted Criterion A.</p> Conclusion <p>These preliminary findings suggest the validity and reliability of this questionnaire, which indicates that it may be useful as a foundational resource and contribute to the advancement of this field.</p> <p><i>Level of evidence</i> III: Retrospective observational study.</p>