药师（英语：Pharmacist），是提供药物知识及药事服务的专业人员。

「药剂师」之名称源自于日本，很多周边国家沿用至今。但近年受到西方国家之影响，药师的职责除了调配药剂外，已进化到全面药事照护的阶段，所以韩国、**和中国大陆等地开始将其正名为药师。

药师是药学知识的专家，也是解答民众有关药物问题的最适当人选。药师会根据病患的病历记录、医师的诊断，为病患选择最适合的药物剂型（如：散剂、胶囊剂、溶液剂、栓剂等）、剂量（如：老人、肝病或肾病患者需根据其病情增加或降低剂量）。同时他们亦会教导病患服用药物的注意事项和服用方法。

Pharmacists, also known as chemists (Commonwealth English) or druggists (North American and, archaically, Commonwealth English), are healthcare professionals who practice in pharmacy, the field of health sciences focusing on safe and effective medication use. A pharmacist is a member of the health care team directly involved with patient care. Pharmacists undergo university-level education to understand the biochemical mechanisms and actions of drugs, drug uses, therapeutic roles, side effects, potential drug interactions, and monitoring parameters. This is mated to anatomy, physiology, and pathophysiology. Pharmacists interpret and communicate this specialized knowledge to patients, physicians, and other health care providers.