The chemical etching behavior for the lines consisting of Er 3+ -doped CaF 2 nanocrystals patterned on the surface of an oxyfluoride glass by using a laser-induced crystallization technique (laser: Yb-doped YVO 4 ; wavelength: 1080nm; power: 1.7W; a scanning speed: 2μm/s) in a nitric acid solution (1N HNO 3 ) is examined, and the morphology change in the lines due to the etching is characterized from confocal laser microscope observations and photoluminescence (PL) spectrum measurements of Er 3+ ions. The higher and wider bumps compared with the bump of the original line (no etching) are observed in etched lines, and in particular, the surrounding of lines is etching away preferentially, forming the groove in both sides of line. PL spectra of Er 3+ ions with strong intensities are observed from etched lines, suggesting that Er 3+ -doped CaF 2 nanocrystals are largely present just at the surface of etched lines. It is found that the chemical etching rate (1.2×10 −2 μm/min) of the crystallized bulk sample is smaller than that (5.4×10 −2 μm/min) of the precursor bulk glass, suggesting that CaF 2 nanocrystals formed have a high resistance against the chemical attack.