An information processor for extracting a fetal cardiac potential signal from among a plurality of biopotential signals derived from both a mother and a fetus, such as a portable information processor, said information processor comprising: a selecting module configured to select, from among said plurality of biopotential signals derived, a biopotential signal containing a high proportion of maternal cardiac potential signals; an independent component analysis module configured to perform independent component analysis on the plurality of biopotential signals and to output a plurality of signals having periods or phases different from each other; a periodic signal detection module (34, 39) configured to detect as a first peak time signal, from a biopotential signal selected by the selecting module, a signal having periodic peaks when the variance of peak intervals between the peak times is a predetermined reference variance value or less, and to detect, as second peak time signals, among signals output from the independent component analysis module, one or more signals having periodic peaks when the variance of peak intervals between the peak times is a predetermined reference variance value or less; an output signal selecting module configured to acquire the first peak time signal as reference input and also acquire the one or more second peak time signals as comparison input, so as to select from among the one or more second peak time signals a signal having a difference in average periods equal to or larger than a predetermined reference value from those of the first peak time signal, as a fetal cardiac potential signal, whereby if there is no signal having a difference in average periods equal to or larger than the predetermined reference value, the output signal selecting module is configured to select a signal having a difference in phases equal to or larger than a predetermined reference value from those of the first peak time signal, as a fetal cardiac potential signal; and a module configured to output the fetal cardiac potential signal selected by the output signal selecting module. a selecting module configured to select, from among said plurality of biopotential signals derived, a biopotential signal containing a high proportion of maternal cardiac potential signals; an independent component analysis module configured to perform independent component analysis on the plurality of biopotential signals and to output a plurality of signals having periods or phases different from each other; a periodic signal detection module (34, 39) configured to detect as a first peak time signal, from a biopotential signal selected by the selecting module, a signal having periodic peaks when the variance of peak intervals between the peak times is a predetermined reference variance value or less, and to detect, as second peak time signals, among signals output from the independent component analysis module, one or more signals having periodic peaks when the variance of peak intervals between the peak times is a predetermined reference variance value or less; an output signal selecting module configured to acquire the first peak time signal as reference input and also acquire the one or more second peak time signals as comparison input, so as to select from among the one or more second peak time signals a signal having a difference in average periods equal to or larger than a predetermined reference value from those of the first peak time signal, as a fetal cardiac potential signal, whereby if there is no signal having a difference in average periods equal to or larger than the predetermined reference value, the output signal selecting module is configured to select a signal having a difference in phases equal to or larger than a predetermined reference value from those of the first peak time signal, as a fetal cardiac potential signal; and a module configured to output the fetal cardiac potential signal selected by the output signal selecting module.