An information writable film applicable to the surface of a target, the color of the area of the target where the information to be written by a laser marking is not limited and a mark written in the information writable film is white, comprising: a writable film layer made of light-transmissive material formed in a film shape, wherein a color former including a photo-sensitive composition or a heat-sensitive composition which is changeable from the black color with light transmission ratio 0% to 95% or a transparent state to a white color state by shifting its physical characteristic or its chemical characteristic by irradiating a particular wavelength laser beam, mixed with a transparent plastic resin having chemical resistance and structural strength; and a reading assistance layer under the writable film layer, which color is darker black having lower light transmission ratio than that of the writable film layer or black, and having adhesiveness to the surface of the target; wherein the writable film layer with the reading assistance layer as two layers is obtained, in order to enhance chemical resistance and structural strength, by mixing with the transparent plastic resin, and, in order to avoid deterioration of the contrast ratio due to mixing with the transparent plastic resin, superimposing the black color of the reading assistance layer, and wherein an anti-heat contraction black layer having black color or dark color and having higher rigidity than that of the writable film layer is applied under the writable film layer as the reading assistance layer, which serves both as the component for absorbing heat generated in the writing process of the identification code by the laser beam to the writable film layer and as the component for prevention of the heat contraction by its rigidity and as the component for enhancing the contrast ratio by its black or dark color. a writable film layer made of light-transmissive material formed in a film shape, wherein a color former including a photo-sensitive composition or a heat-sensitive composition which is changeable from the black color with light transmission ratio 0% to 95% or a transparent state to a white color state by shifting its physical characteristic or its chemical characteristic by irradiating a particular wavelength laser beam, mixed with a transparent plastic resin having chemical resistance and structural strength; and a reading assistance layer under the writable film layer, which color is darker black having lower light transmission ratio than that of the writable film layer or black, and having adhesiveness to the surface of the target; wherein the writable film layer with the reading assistance layer as two layers is obtained, in order to enhance chemical resistance and structural strength, by mixing with the transparent plastic resin, and, in order to avoid deterioration of the contrast ratio due to mixing with the transparent plastic resin, superimposing the black color of the reading assistance layer, and wherein an anti-heat contraction black layer having black color or dark color and having higher rigidity than that of the writable film layer is applied under the writable film layer as the reading assistance layer, which serves both as the component for absorbing heat generated in the writing process of the identification code by the laser beam to the writable film layer and as the component for prevention of the heat contraction by its rigidity and as the component for enhancing the contrast ratio by its black or dark color.