Background Information exchange between hospitals and primary care physicians is suboptimal. Most physicians are dissatisfied with the current referral process, and poor communication leads to negative care transition outcomes. Method To identify the key information needed for a successful transition of care, we conducted a qualitative study using consecutive, semistructured in‐person interviews and focus group sessions. We recruited five participants engaged in clinical work for individual interviews and 16 participants for focus groups. We analyzed all data using qualitative thematic analysis. All results were returned to the participants and modified based on their feedback. Results The five individual interviews provided a general picture of the current referral process and an interview guide for the following focus group sessions. The focus group discussions were used to identify the essential information needed at admission and discharge from the hospital. Essential information on hospital admission was as follows: (1) basic medical and care information, (2) care resources available at home, (3) the purpose of admission and the goals of care during hospitalization, and (4) status of advance care planning (ACP) and patient's will in an emergency. Essential information on hospital discharge was as follows: (1) clinical course, (2) explanation of medical condition during hospitalization, (3) status of ACP and patient's will in an emergency, and (4) medical procedures to be continued at home. Conclusions We identified the essential information needed for a successful transition of care in Japan. The clinical effectiveness of a template that contains the information identified in our study warrants further investigation.