Scanning projection device PJ two-dimensionally deflects a beam emitted from light source unit 1 and performs scanning with deflection element 3, and projects the beam obliquely on screen SC with projection optical system 7. By defining a range of an incident angle to screen SC properly, projection optical system 7 does not disturb an observation of images, and a correction of a spot shape does not become difficult. Further, by defining a ratio of scan-angle magnifications between in the vertical direction and the horizontal direction properly, difference in resolution between in the vertical direction and the horizontal direction can be reduced, and a high-quality and excellent image can be displayed, even when a beam obliquely projected.