The purpose of this thesis is to examine idiomatic structures with ki in the ki-wo [transitive verb] and ki-ga [intransitive verb] constructions. It is argued that for Japanese language learners, it is crucial to be able to understand and produce ki idioms, because they are frequently used in everyday speech. There are often misconceptions regarding ki in the West for those who are fans of Japanese culture due to the influence of martial arts and anime, which paint ki as a spiritual energy that can be controlled and developed. However, upon examining the above mentioned idiomatic structures with ki, it is clear that ki can be expressed as both controllable by the subject of ki (transitive), as well as a thing that acts of its own accord and is spontaneous (intransitive). This thesis somewhat corroborates the studies of W. M. Jacobson, Zoe Pei Sui Luk , and Yoshihiko Ikegami by arguing that intransitive constructions are often used in Japanese, and examining both transitive and intransitive expressions with ki is significant to understanding the meanings produced in ki expressions. It is hoped that analyzing 37 transitive and intransitive idiomatic structures with ki will help Japanese language learners not only understand the syntactic and semantic aspects of transitivity in the Japanese language, but also to help these L2 learners conceptualize the abstract noun ki, which can be defined in so many different ways in a dictionary.