The purposes of the present study were to develop a Parenting Scale of Inconsistency and to evaluate its initial reliability and validity. The 12 items assess the inconsistency among parents' moods, behaviors, and attitudes toward children. In the primary study, 517 participants completed three measures: the new Parenting Scale of Inconsistency, the Parental Bonding Instrument, and the Depression Scale of the General Health Questionnaire. The Parenting Scale of Inconsistency had good test-retest reliability of .85 and internal consistency of .88 (Cronbach coefficient α). Construct validity was good as Inconsistency scores were significantly correlated with the Care and Overprotection scores of the Parental Bonding Instrument and with the Depression scores. Moreover, Inconsistency scores' relation with a dimension of parenting style distinct from Care and Overprotection suggested that the Parenting Scale of Inconsistency had factorial validity. This scale seems a potential measure for examining the relationships between inconsistent parenting and the mental health of children.