An image decoding method for decoding coded blocks in raster-scan order, the method comprising: a first step for performing inverse variable length coding processing; a second step for inverse quantization processing the data that has been processed in the first step; a third step for decoding prediction residuals by inverse frequency conversion processing the data obtained by inverse quantization in the second step; and a fourth step for obtaining a decoded image including decode target pixels by performing a decoding process using a prediction mode selected among a plurality of prediction modes including a first intra prediction mode, a second intra prediction mode, and an inter prediction mode, wherein, a decoding process using the first intra prediction mode in the fourth step includes a first process for generating a first reference pixel, and for generating a prediction pixel using the first reference pixel and a decoded second reference pixel which is decoded before the decoding process for the decode target pixels in the first intra prediction mode, wherein the first reference pixel is located at a boundary of a decode target block in the first intra prediction mode, wherein for generating the first reference pixel in the first process, at least one generating method is executed among generating methods including a generating method generating a plurality of first reference pixels located in line in a vertical direction by using at least one pixel located at a boundary of a decoded block adjacently located on an upper side of the decode target block and a generating method generating a plurality of first reference pixels located in line in a horizontal direction by using at least one pixel located at a boundary of a decoded block adjacently located on a left side of the decode target block in the first intra prediction mode, wherein in the first process for generating a prediction pixel, a calculation process is performed using the first reference pixel and the decoded second reference pixel for generating a prediction pixel located between the first reference pixel and the decoded second reference pixel, the second reference pixel being adjacently located on left side or upper side of the decode target block and located at a different side from the side of the first reference pixel in the first intra prediction mode, and wherein a decode target pixel is obtained by using the prediction pixel generated by the first process and the prediction residuals in the first intra prediction mode, wherein the second intra prediction mode in the fourth step is an intra prediction mode that uses a unidirectional method in which pixels in a prediction direction in a decode target block are predicted by a value of one reference pixel, and is a different intra prediction mode from the first intra prediction mode. a first step for performing inverse variable length coding processing; a second step for inverse quantization processing the data that has been processed in the first step; a third step for decoding prediction residuals by inverse frequency conversion processing the data obtained by inverse quantization in the second step; and a fourth step for obtaining a decoded image including decode target pixels by performing a decoding process using a prediction mode selected among a plurality of prediction modes including a first intra prediction mode, a second intra prediction mode, and an inter prediction mode, wherein, a decoding process using the first intra prediction mode in the fourth step includes a first process for generating a first reference pixel, and for generating a prediction pixel using the first reference pixel and a decoded second reference pixel which is decoded before the decoding process for the decode target pixels in the first intra prediction mode, wherein the first reference pixel is located at a boundary of a decode target block in the first intra prediction mode, wherein for generating the first reference pixel in the first process, at least one generating method is executed among generating methods including a generating method generating a plurality of first reference pixels located in line in a vertical direction by using at least one pixel located at a boundary of a decoded block adjacently located on an upper side of the decode target block and a generating method generating a plurality of first reference pixels located in line in a horizontal direction by using at least one pixel located at a boundary of a decoded block adjacently located on a left side of the decode target block in the first intra prediction mode, wherein in the first process for generating a prediction pixel, a calculation process is performed using the first reference pixel and the decoded second reference pixel for generating a prediction pixel located between the first reference pixel and the decoded second reference pixel, the second reference pixel being adjacently located on left side or upper side of the decode target block and located at a different side from the side of the first reference pixel in the first intra prediction mode, and wherein a decode target pixel is obtained by using the prediction pixel generated by the first process and the prediction residuals in the first intra prediction mode, wherein the second intra prediction mode in the fourth step is an intra prediction mode that uses a unidirectional method in which pixels in a prediction direction in a decode target block are predicted by a value of one reference pixel, and is a different intra prediction mode from the first intra prediction mode.