  With the smearing technique, the three-quark (3Q) ground-state potential
$V_{\rm 3Q}$ is numerically extracted in the SU(3)$_c$ lattice QCD Monte Carlo
simulation with $12^3 \times 24$ and $\beta=5.7$ at the quenched level. With
accuracy better than a few %, $V_{\rm 3Q}$ is well described by a sum of a
constant $C_{\rm 3Q}$, the two-body Coulomb part $-A_{\rm 3Q}\sum_{i<j}
\frac1{|{\bf r}_i-{\bf r}_j|}$ and the three-body linear confinement part
$\sigma_{\rm 3Q} L_{\rm min}$, where $L_{\rm min}$ denotes the minimal length
of the color flux tube linking the three quarks. By comparing with the Q-$\bar
{\rm Q}$ potential, we find a universal feature of the string tension as
$\sigma_{\rm 3Q} \simeq \sigma_{\rm Q \bar Q}$ and the one-gluon-exchange
result for the Coulomb coefficient as $A_{\rm 3Q} \simeq \frac12 A_{\rm Q \bar
Q}$. All our results including the constant term are consistent with the
requirement on the diquark limit in the lattice regularization.
