  We study the spatial correlation of a particle-hole pair in the isovector
channel in $^{56}$Co and $^{40}$K nuclei. To this end, we employ the
Hartree-Fock+Tamm-Dancoff approximation with the Skyrme interaction. We find a
large concentration of the two-body density at positions where the neutron
particle and the proton hole states locate on the opposite side to each other
with respect to the core nucleus. This feature originates from a repulsive
nature of the isovector residual interaction, which is in stark contrast to the
dineutron correlation with an attractive pairing interaction between the
valence neutrons discussed e.g., in $^{11}$Li and $^6$He. A possible
experimental implication of the repulsive correlation is also discussed.
