In an image coding apparatus (1), a Hadamard transform unit (11) performs horizontal Hadamard transform on a picture of uncompressed image data (21). The sum total of absolute values of AC component values obtained by the Hadamard transform is calculated as a Hadamard value (23) of the picture. A scene change determination unit (12) determines whether a scene change occurs or not in the picture on the basis of the Hadamard value (23). In a case where a scene change occurs in the picture or where a differential absolute value between the amount of generated codes in a coded GOP and the ideal amount of codes in a GOP is larger than a predetermined reference value, a quantization parameter determination unit (13) determines a quantization parameter (24) of the picture on the basis of the Hadamard value (23) and the target amount of codes of the picture. A coding unit (14) codes the picture by using the determined quantization parameter (24).