A program causing a computer to execute an image coding method for coding a video signal using a processor, said image coding method comprising: classifying a plurality of images included in the video signal into layers, each of the plurality of images belonging to a corresponding one of the layers, the layers including a first layer and a second layer; wherein (i) when an image belonging to the first layer is coded, the image belonging to the first layer is (a) able to refer to another image belonging to the first layer and (b) is not able to refer to an image belonging to the second layer; and (ii) when an image belonging to the second layer is coded, the image belonging to the second layer is able to (a) refer to an image belonging to the first layer and (b) another image belonging to the second layer; the method further comprising coding (i) a first image belonging to the first layer by referring to another image belonging to the first layer and (ii) a second image belonging to one of the first layer and the second layer by inter prediction, wherein the second image precedes the first image in coding order; and coding a third image belonging to the second layer by inter prediction, wherein the third image follows the first image in the coding order; characterized in that in a case that the first image is a specified image to prohibit the third image from referring to the second image, the third image is coded without referring to the second image preceding the first image in the coding order; and in a case that the first image is not the specified image to prohibit the third image from referring to the second image, the third image is able to be coded by referring to the second image preceding the first image in the coding order. classifying a plurality of images included in the video signal into layers, each of the plurality of images belonging to a corresponding one of the layers, the layers including a first layer and a second layer; wherein (i) when an image belonging to the first layer is coded, the image belonging to the first layer is (a) able to refer to another image belonging to the first layer and (b) is not able to refer to an image belonging to the second layer; and (ii) when an image belonging to the second layer is coded, the image belonging to the second layer is able to (a) refer to an image belonging to the first layer and (b) another image belonging to the second layer; (i) when an image belonging to the first layer is coded, the image belonging to the first layer is (a) able to refer to another image belonging to the first layer and (b) is not able to refer to an image belonging to the second layer; and (ii) when an image belonging to the second layer is coded, the image belonging to the second layer is able to (a) refer to an image belonging to the first layer and (b) another image belonging to the second layer; the method further comprising coding (i) a first image belonging to the first layer by referring to another image belonging to the first layer and (ii) a second image belonging to one of the first layer and the second layer by inter prediction, wherein the second image precedes the first image in coding order; and coding a third image belonging to the second layer by inter prediction, wherein the third image follows the first image in the coding order; characterized in that in a case that the first image is a specified image to prohibit the third image from referring to the second image, the third image is coded without referring to the second image preceding the first image in the coding order; and in a case that the first image is not the specified image to prohibit the third image from referring to the second image, the third image is able to be coded by referring to the second image preceding the first image in the coding order.