According to the present invention, a means of estimating the place of origin of a test subject by quickly and conveniently determining the genome type of JC virus infecting a test subject is provided. The present invention relates to a set of oligonucleotide probes for determining the genome type of JC virus infecting a test subject, such set containing: oligonucleotide probes (a-1) and (a-2); oligonucleotide probes (b-1) and (b-2); oligonucleotide probes (c-1) and (c-2); oligonucleotide probes (d-1), (d-2), (d-3), and (d-4); oligonucleotide probes (e-1), (e-2), and (e-3); oligonucleotide probes (f-1), (f-1), and (f-3); oligonucleotide probes (g-1), (g-2), and (g-3); oligonucleotide probes (h-1), (h-2), (h-3), and (h-4); oligonucleotide probes (i-1) and (i-2); oligonucleotide probes (j-1), (j-2), and (j-3); oligonucleotide probes (k-1), (k-2), and (k-3); and oligonucleotide probes (l-1) and (l-2).