An entropy encoding apparatus comprises: a binarization unit configured to convert an input syntax element into binarized data; a context calculation unit configured to generate a context index; a context memory unit configured to hold context information; and an arithmetic coding unit configured to perform arithmetic coding using context information output corresponding to the generated context index, and the binarized data, is provided. The context memory unit comprises: a storage unit, an initial value generation unit configured to generate an initial value of context information, a control unit configured to output a control signal specifying which to select between the initial value and the context information which corresponds to the generated context index, a selection unit configured to select either of the initial value or the context information which corresponds to the generated context index, an updating unit configured to generate updated context information.