Objective: Psychosocial interventions during nursing consultations emotionally support and inform patients undergoing cancer diagnosis. In Japan, certified nurse specialists (CNSs) and certified nurses (CNs) mainly provide nursing consultations. Using communication skills in therapeutic nurse-patient relationships is an effective advanced nursing practice when performed consciously. We developed a scale to measure the frequency of oncology nurses' intentional use of communication skills in the initial oncology nursing consultation after a cancer diagnosis. Methods: Based on a literature review, we identified nine initial dimensions and developed a 32-item questionnaire. After the focus group interviews and pilot study between January and March 2018, the final questionnaire was administered to CNSs and CNs who offered nursing consultations to patients with cancer in Japanese hospitals. The properties of all scales and subscales were assessed using item-to-item and mean item-to-item correlations. The reliability was evaluated using Cronbach's alpha. Construct validity was assessed using exploratory factor analysis, correlations between all scales and characteristics, and contrast group comparisons. Results: The communication skills scale comprised 29 items across six dimensions of communication skills: Exploring, Listening, Acceptance, Silence, Approval, and Empathy. The scale has good reliability and validity. Conclusions: This scale is a valid and reliable item for self-assessing nurses' communication skills in the initial oncology nursing consultation after a cancer diagnosis.