  We have measured temperature dependence of thermoelectric power (TEP) on
MgB$_2$ superconductor under hydrostatic pressure. The sign and temperature
dependence of TEP shows metallic hole carriers are dominant with activation
type contribution at higher temperature. TEP increases with pressure while
$T_c$ decrease with ratio -0.136 K/kbar. The data are discussed in
consideration of carriers from different bands and anisotropy of
compressibility.
