The present invention can suppress the generated code quantity for each image increment so as not to exceeding the target code quantity without having a usage quantizing factor deviate greatly in a sure manner.An image encoding device (200) determines a basic quantization parameter (QPMB) serving as a basic quantizing factor to be predicted in the case that the main encoding generated code comes near the target code quantity at the time of encoding an input image (91). The image encoding device (200) encodes the input image (91) for each feedback control increment by executing quantization using an adapted quantization parameter (QPt) based on an average quantization parameter BaseQP serving as a usage quantizing factor determined based on at least the basic quantization parameter (QPMB). The image encoding device (200) confirms the generated code quantity of the encoded input image (91) for each feedback control increment, and in the case of predicting that the generated code quantity for each image increment will exceed the target code quantity, increases the value of the adapted quantization parameter (QPt) by increasing the average quantization parameter BaseQP.