An apparatus for transcoding a coded moving picture sequence according to the present invention comprises a rate controller for adapting the scaling factor to perform the rate control over the coded moving picture sequence signal having a desired target bit rate. The rate controller of the apparatus has: a remaining bit computing unit for computing: a remaining number of inputting bits R.sub.in (n) for each of the pictures in the first coded moving picture sequence signal on the basis of the number of real inputting bits S.sub.in (n) of the current picture and the estimated number of inputting bits; and a remaining number of outputting bits R.sub.out (n) for each of the pictures in the second coded moving picture sequence signal on the basis of the number of real outputting bits S.sub.out (n) of the current picture and the estimated number of outputting bits; a target ratio computing unit for computing, for each of the pictures, a target ratio of the remaining number of outputting bits R.sub.out (n) to the remaining number of inputting bits of the picture R.sub.in (n); and a scaling factor computing unit for computing the scaling factor on the basis of the target ratio to control the target bit rate of the second coded moving picture sequence signal.