It is possible to observe imaging subjects, such as cells or the like, without causing an increase in the apparatus size. Provided is an observation apparatus (1) including: a flat-plate-like stage (3) formed of an optically transparent material on which a container (2) accommodating a sample (P) is placed; a deflecting member (8) that is disposed below the stage (3) and that deflects light coming from the sample (P) on the stage (3) into a substantially horizontal direction; an objective lens (9) that collects the light deflected by the deflecting member (8); and an image-acquisition device (10) that captures the light collected by the objective lens (9).