A decoding apparatus includes a state variable calculation unit which
calculates a second state variable based on a first context variable and
a first state variable which are stored in a first memory unit and a
second memory unit, respectively, and determines a selection signal
representing a symbol as a result of arithmetic decoding processing. A
context variable calculation unit calculates a second context variable
based on the first context variable and the selection signal and updates
the first memory unit. A re-normalization unit calculates a third state
variable by using the coded data and the second state variable and
updates the second memory unit. The state variable calculation unit
outputs the determined selection signal that is usable in processing of a
succeeding step without waiting for the operations of the context
variable calculation unit and the re-normalization unit.