This study aimed to clarify what primary care physicians (PCPs) in Japan understand of the role of physical therapists (PTs) through the experience of working with PTs in hospitals, and what roles PCPs expect for PTs in future primary care. Semi-structured interviews were conducted individually with 9 purposively sampled PCPs with sufficient experience of collaboration with PTs. Interview data were analyzed by theme analysis focusing on "What does the PCP understand about the role of PTs through the experience of working with PTs in hospitals?" and "What roles and purposes does the PCP wish for PTs in primary care settings?" PCPs viewed PTs as providers of rehabilitation in the traditional medical model, and understood their role as an occupation having a mono-causal viewpoint, namely a specific and well-defined outcome for individual patients, and intervening with patients within a short clinical course with the aim of improvement or maintenance of the patient's condition. With regard to future primary care, PCPs expected that PTs would interpret various factors related to patient lives from the viewpoint of causal interactions; become important stakeholders in the community; and respond flexibly to patients and the environmental factors around them with continued support to the individual. PCPs understood the role of PTs in hospitals as "Rehabilitation in the traditional medical model," and expected the future role of PTs in primary care as "Rehabilitation in integrated community care."