A highly reliable semiconductor device includes, for example, a memory circuit MEM such as a multiport RAM and a BIST circuit (BIST[A] and BIST[B]) for carrying out a test for each of the ports PO[A] and PO[B] of the MEM, as well as pointers PNT0[A] to PNT3[A] and PNT0[B] to PNT3[B] corresponding to the PO[A] and PO[B], respectively. Each of the BIST[A] and BIST[B] manages plural respective segments SEG0 to SEG3 obtained by dividing the MEM and the PNT0[A] to PNT3[A] are provided for those SEG0 to SEG3, respectively. For example, the BIST[A], upon accessing SEG0, writes `1` in PNT0[A] while the BIST[B] refers to the value in this PNT0[A], thereby its access to SEG0 can be avoided. Consequently, each port can execute a complicated test pattern asynchronously.