A disclosed AD conversion circuit includes a holding portion storing sequence information, signal selection information and time information; a sequencing counter to be initialized by receiving a timing signal output at a predetermined period and counting upon receipt of a matching signal to obtain a sequencing counter count value; a time period counter to be initialized by receiving the timing signal or the matching signal and counting a time period counter count value; a comparator generating the matching signal when the time information matches the time period counter count value after comparison by referring to the sequence information using the sequencing counter count value; a selecting portion selecting analog signals of one type corresponding to the signal selection information obtained by referring to the sequence information using the sequencing counter count value out of analog signals of various types; and an AD converter converting the selected analog signals.