A prism unit, which is capable of firmly fixing a plurality of prism parts in a small space, and a laser device, which is capable of enhancing output power of laser light with use of the prism unit, are provided. For this purpose, a prism unit (28) includes a plurality of prism parts (35), which refract incident light (21), and a fixed part (36) which is fixed to or formed integrally with at least two of the plurality of prism parts. Further, a laser device includes the prism unit (28), and only a wavelength in a desired range out of a plurality of oscillation wavelengths is selectively oscillated by the prism unit.