An image quantization parameter encoder includes: a prediction unit 11 for generating a predicted quantization parameter from a past reconstructed quantization parameter; a computing unit 12 for generating a delta quantization parameter from a quantization parameter and the predicted quantization parameter; and a quantization parameter encoding unit 13 for binary arithmetic encoding a first bin indicating whether or not the delta quantization parameter is significant, one or more other bins indicating an absolute value of the delta quantization parameter and made non-redundant, and a bin indicating whether the delta quantization parameter is positive or negative, in the case where the delta quantization parameter is significant.