A decoding apparatus for decoding a bitstream including a core parameter, a tone parameter, and a floor parameter, the core parameter being a low-band portion of an encoded input sound signal, the tone parameter indicating a magnitude of energy of a tone component of a high-band signal, the floor parameter indicating a magnitude of energy of a floor component obtained by subtracting the tone component from the high-band signal, the high-band signal representing a high-band portion of the encoded input sound signal, the decoding apparatus comprising: a decoding unit (501 901) configured to decode the core parameter to generate a decoded narrowband signal (x(n)); a QMF analysis unit configured to convert the decoded narrowband signal obtained from the core parameter into a subband signal (X(ts,sb)), a splitter (503 903) which generates a low-band tone signal (X T (ts,sb)) representing a tone component of the decoded narrowband signal and a low-band floor signal (X F (ts,sb)) representing a floor component of the decoded narrowband signal by splitting the subband signal (X(ts,sb)) into the low-band tone signal (X T (ts,sb)) and the low-band floor signal (X F (ts,sb)); a tone extension unit (504 904) configured to generate a high-band tone signal (X' T (ts,sb)) corresponding to the tone component of the high-band signal, using the low-band tone signal; a floor extension unit (505 905) configured to generate a high-band floor signal (X' F (ts,sb)) corresponding to the floor component of the high-band signal, using the low-band floor signal by patching the low-band floor signal X F (ts, sb) to a high-frequency portion, to generate the high-band floor signal X' F (ts, sb); a tone adjustment unit (506 906) configured to adjust the high-band tone signal using the tone parameter to generate an adjusted tone signal (X" T (ts,sb)); a floor adjustment unit (507 907) configured to adjust the high-band floor signal using the floor parameter to generate an adjusted floor signal (X" F (ts,sb)); and an addition unit (508 908) configured to add the subband signal (X(ts,sb)) obtained from the core parameter, the adjusted tone signal (X" T (ts,sb)), and the adjusted floor signal (X" T (ts,sb)), to generate a bandwidth extended signal (X"(ts,sb)); and characterised in that the tone extension unit is configured to select, from among subbands of the low-band tone signal (X T (ts,sb)), a subband having a tone component whose energy is (i) greater than a predetermined multiple of energy of a tone component of an adjacent subband and (ii) greater than a predetermined multiple of energy of a floor component of the selected subband, and replicate the low-band tone signal corresponding to the selected subband onto a subband which is an integral multiple of the selected subband, to generate the high-band tone signal. a decoding unit (501 901) configured to decode the core parameter to generate a decoded narrowband signal (x(n)); a QMF analysis unit configured to convert the decoded narrowband signal obtained from the core parameter into a subband signal (X(ts,sb)), a splitter (503 903) which generates a low-band tone signal (X T (ts,sb)) representing a tone component of the decoded narrowband signal and a low-band floor signal (X F (ts,sb)) representing a floor component of the decoded narrowband signal by splitting the subband signal (X(ts,sb)) into the low-band tone signal (X T (ts,sb)) and the low-band floor signal (X F (ts,sb)); a tone extension unit (504 904) configured to generate a high-band tone signal (X' T (ts,sb)) corresponding to the tone component of the high-band signal, using the low-band tone signal; a floor extension unit (505 905) configured to generate a high-band floor signal (X' F (ts,sb)) corresponding to the floor component of the high-band signal, using the low-band floor signal by patching the low-band floor signal X F (ts, sb) to a high-frequency portion, to generate the high-band floor signal X' F (ts, sb); a tone adjustment unit (506 906) configured to adjust the high-band tone signal using the tone parameter to generate an adjusted tone signal (X" T (ts,sb)); a floor adjustment unit (507 907) configured to adjust the high-band floor signal using the floor parameter to generate an adjusted floor signal (X" F (ts,sb)); and an addition unit (508 908) configured to add the subband signal (X(ts,sb)) obtained from the core parameter, the adjusted tone signal (X" T (ts,sb)), and the adjusted floor signal (X" T (ts,sb)), to generate a bandwidth extended signal (X"(ts,sb)); and characterised in that the tone extension unit is configured to select, from among subbands of the low-band tone signal (X T (ts,sb)), a subband having a tone component whose energy is (i) greater than a predetermined multiple of energy of a tone component of an adjacent subband and (ii) greater than a predetermined multiple of energy of a floor component of the selected subband, and replicate the low-band tone signal corresponding to the selected subband onto a subband which is an integral multiple of the selected subband, to generate the high-band tone signal.