A scalable coding apparatus comprising: a core layer coding section that is adapted to generate core layer encoded data frames using an input speech signal; a deciding section that is adapted to identify a speech mode of the input speech signal, the speech mode being from a plurality of predefined speech modes; and an enhancement layer coding section (104, 105, 106) that is adapted to generate, using the input speech signal, quality improving encoded data that is to improve quality of a decoded signal frame when the decoding is performed with the core layer encoded data for a frame with same number, and that is to generate encoded data for packet loss concealment, which is to be used for repairing a previous decoded signal frame when the core layer encoded data of a previous frame has become lost or erroneous before the decoding; and characterized by a bit distributing section that is adapted to perform bit allocation based on the identified speech mode by judging whether to assign certain bits for the quality improving encoded data or for the encoded data for packet loss concealment, and generate enhancement layer bit allocation information based on a result of the bit allocation, and wherein: the enhancement layer coding section is configured to generate the quality improving encoded data with a plurality of enhancement layers including a low and at least one higher enhancement layers, and set the quality improving encoded data, the J encoded data for packet loss concealment and the enhancement layer bit allocation information in a same transmission packet; and the bit distributing section is adapted to reduce a number of bits to be assigned for the quality improving encoded data of a higher enhancement layer by an adjustment number and increase a number of bits assigned for the encoded data for packet loss concealment in accordance with said adjustment number of bits, when level of quality improvement of the decoded signal by the quality improving encoded data of the higher enhancement layer before the reduction of said number of bits is less than by the quality improving encoded data of the low enhancement layer; said enhancement layer bit allocation information designating said number of bits assigned for the encoded data for packet loss concealment in said higher enhancement layer. a core layer coding section that is adapted to generate core layer encoded data frames using an input speech signal; a deciding section that is adapted to identify a speech mode of the input speech signal, the speech mode being from a plurality of predefined speech modes; and an enhancement layer coding section (104, 105, 106) that is adapted to generate, using the input speech signal, quality improving encoded data that is to improve quality of a decoded signal frame when the decoding is performed with the core layer encoded data for a frame with same number, and that is to generate encoded data for packet loss concealment, which is to be used for repairing a previous decoded signal frame when the core layer encoded data of a previous frame has become lost or erroneous before the decoding; and the enhancement layer coding section is configured to generate the quality improving encoded data with a plurality of enhancement layers including a low and at least one higher enhancement layers, and set the quality improving encoded data, the J encoded data for packet loss concealment and the enhancement layer bit allocation information in a same transmission packet; and the bit distributing section is adapted to reduce a number of bits to be assigned for the quality improving encoded data of a higher enhancement layer by an adjustment number and increase a number of bits assigned for the encoded data for packet loss concealment in accordance with said adjustment number of bits, when level of quality improvement of the decoded signal by the quality improving encoded data of the higher enhancement layer before the reduction of said number of bits is less than by the quality improving encoded data of the low enhancement layer; said enhancement layer bit allocation information designating said number of bits assigned for the encoded data for packet loss concealment in said higher enhancement layer.