To provide a coder of an information source, which can efficiently code information in which the property locally differs and to provide a decoder, a coding method and a decoding method.

The information coder is provided with a context generator 1 that generates a context signal 101 from a reproduced coding symbol 109, a prediction device 2 that generates a prediction signal 106 and a prediction error signal 103 on the basis of the context signal 101, a quantizer 3 that quantizes the prediction error signal 103 to generate a quantized prediction error signal 104, a coder 4 that codes the quantized prediction error signal 104, an inverse quantizer 5 that applies inverse quantization to the quantized prediction error signal 104 to generate a reproduction prediction error signal 107, a prediction inverse converter 6 that applies prediction inversion conversion to the reproduction prediction error signal 107 to generate a reproduction sampling signal 108, a sub sample control circuit 8 that generates a sub sample signal 110 to control whether or not a coded symbol 102 is to be sub sampled, and an interpolator that interpolates the reproduction sampling signal 108 corresponding to the sub sampled coding symbol 102.