The purpose of this study is to show the process by which I, as a caregiver of infants, began to “sing” with infants. Based on my subjective and intersubjective understanding, I present the structure of the process by which infants around the age of two and caregivers engage in “singing.” I was a caregiver of a class of one-year-old children at B nursery School in City A and wrote 104 “episode descriptions.” From these, I selected 2-yearold Naoki’s “episode description” and analyzed it from the viewpoint of how he engaged in “singing.” I also illustrated the process by which Naoki and the author engaged in “singing” together. The results showed that there are five stages in the process of “singing” for infants around the age of two and their caregivers: (1) expansion stage for others to “sing,” (2) attachment stage for “singing,” (3) establishment stage for “singing” relationships, (4) attachment stage for “singer,” and (4) expansion stage for “singing” relationships. It was found that the musicality of “singing” and the fundamental consideration of caregivers led to the repetition of “singing” activities and the construction of mutually complementary “singing” relationships between infants and caregivers. Further, we found that “singing” relationships between infants and caregivers extended to “singing” relationships between infants.