Provided is a crystal of a specific oxazole compound that has specific inhibitory activity against PDE4, and that shows excellent stability. Specifically, provided is a crystal of an oxazole compound represented by formula (5)

wherein the crystal has peaks at diffraction angles 2θ(°) of 9.6±0.2, 19.1±0.2, and 21.2±0.2 in an X-ray powder diffraction pattern measured using CuKα characteristic X-rays.