A laser ablation device for forming a thin film includes a vacuum chamber having a gas introduction port through which an oxidating gas is introduced into the chamber, and a light-transmittable section, a target holder disposed in the vacuum chamber for holding a target made of a film forming material of an oxide, an object holder confronting the target holder for holding an object on which the thin film is to be formed, a short wavelength laser which emits a first short wavelength laser light passing to the target in the vacuum chamber through the light-transmittable section from outside of the vacuum chamber, and a short wavelength laser light irradiating device for irradiating the object with a second short wavelength laser light passing into the vacuum chamber through the light-transmittable section from outside of the vacuum chamber. The second short wavelength laser light has an intensity lower than that of the first short wavelength laser light irradiating the target. Alternatively, a short wavelength laser light passing device causes the second short wavelength laser light to pass through the light-transmittable section from outside of the vacuum chamber and then to pass in the vicinity of a surface of the object in the vacuum chamber as approximately parallel to the surface of the object.