Effective leadership depends substantially on how leaders communicate, yet existing measures of communication style lack theoretical coherence and practical usability. This study developed and validated an 18-item short form of the Communication Styles Inventory (CSI) for use in leadership research and practice. Based on a large sample of full-time managers in Japan, we selected highly informative and gender-invariant items across the six CSI dimensions using modern psychometric methods. The resulting short form demonstrated clear factorial validity and reliability in an independent sample. The instrument preserves the conceptual richness of the original CSI while substantially reducing respondent burden. This short form provides a practical tool for assessing leaders’ communication tendencies and can support research examining how communication style functions as a behavioral link between personality and leadership behavior.