A semiconductor device comprises an IC chip body and a package substrate that has thereon many external electrodes arranged in a two-dimensional grid configuration. Groups of signal lines that are likely to emit noise (noisy signal lines) are separated and spaced apart from groups of signal lines that are susceptible to noise (noise susceptible signal lines). Each of the noisy signal lines and noise susceptible signal lines is connected to an associated member of an associated IC pad group separated and spaced apart from other IC pad groups. Further, each of the noisy signal lines and noise susceptible signal lines is connected to an associated member of an associated external electrode group selected from the multiplicity of external electrodes arranged in a two-dimensional grid configuration on the package substrate. Thus, groups of potentially interfering signal lines are mutually separated and spaced apart from one another, thereby suppressing the noise.