A speech recognition apparatus includes a first grammar storage unit configured to store one or more grammar segments, a second grammar storage unit configured to store one or more grammar segments, a first decoder configured to carry out a decoding process by referring to the grammar segment stored in the second grammar storage unit, a grammar transfer unit configured to transfer a trailing grammar segment from the first grammar storage unit to the second grammar storage unit, a second decoder configured to operate in parallel to the grammar transfer unit and carry out the decoding process by referring to the grammar segment stored in the second grammar storage unit, and a recognition control unit configured to monitor the state of transfer of the trailing grammar segment carried out by the grammar transfer unit and activate the both decoders by switching the operation thereof according to the state of transfer of the grammar segment.