A rotation detection device includes a sensor unit including plural magnetic sensors and a housing portion covering the magnetic sensors together. The magnetic sensors each include a plate-shaped detection portion including a magnetic detection element to detect a magnetic field from a detection target member and connection terminals extending out of the detection portion. The magnetic sensors are arranged such that the detection portions are aligned in a plate thickness direction thereof. The magnetic detection element is configured to detect a magnetic field in a direction perpendicular to the plate thickness direction. The sensor unit is positioned such that fore-end portions of the detection portions of the magnetic sensors face toward an axial end face of the detection target member, the fore-end portions being end portions located opposite to the side where the connection terminals extend out.