This quantum cascade laser element comprises: a semiconductor substrate; a semiconductor laminate having a first end surface and a second end surface; a first electrode; a second electrode; and an antireflection film formed on the first end surface. The semiconductor laminate is configured to oscillate laser light having a central wavelength of at least 7.5 μm. The antireflection film includes: an insulating film which is a CeO2 film formed on the first end surface; a first refractive index film which is a YF3 film or a CeF3 film disposed on the reverse side of the insulating film from the first end surface; and a second refractive index film which is formed on the first refractive index film on the reverse side of the first refractive index film from the first end surface, and has a refractive index of greater than 1.8.
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