An OCT device that selectively captures OCT data of a fundus of a subject eye and OCT data of an anterior segment of the subject eye. The OCT device includes a spectroscopic optical system that spectroscopically detects interference light between reference light and reflection light of measurement light irradiated on the subject eye. The spectroscopic optical system includes a collimating system that collimates the interference light, a spectrally dispersive element that spectrally disperses the collimated interference light for each spectral wavelength, an image formation system that forms an image of the interference light for each spectral wavelength on an imaging surface, and a light receiving element disposed on the imaging surface. An object-side focal length of the collimating system is shorter than an image-side focal length of the image formation system.