The purpose of this study was to clarify the differences in coaching behaviors between expert and beginner strength and conditioning (S&C) coaches in Japan using a systematic observation method, i.e., modified Arizona State University Observation Instrument (ASUOI). Participants were three expert S&C coaches (11-25 years of experience) and three beginner S&C coaches (0.3-1 year of experience). As a result, the expert coaches spent more than half of their session time in Concurrent Instruction, Silent Monitoring, Post Instruction, and Other, and the beginner coaches exhibited more than half of their behaviors with Silent monitoring and Other. The beginner coaches spent less time in interacting with and teaching to the athletes compared to the expert coaches. In conclusion, beginner S&C coaches could be advised to engage in acquiring not only professional knowledge but also interpersonal knowledge by effectively incorporating formal, non-formal, and informal learning.