A coding apparatus has a quantizer selected from a quantizer group and being used for coding inputted data, a first code amount calculation circuit for calculating a code amount of codes of the inputted data quantized by the quantizer, a prediction circuit for predicting a quantizer among the quantizer group capable of obtaining a target code amount, in accordance with the code amount calculated by the first code amount calculation circuit, the quantizer predicted by the prediction circuit for quantizing the inputted data, a second code amount calculation circuit for calculating a code amount of codes of the inputted data quantized by the predicted quantizer, and a comparator circuit for comparing the code amount calculated by the second code amount calculation circuit with the target code amount.