  Charm spectroscopy has studied under a string model. Charmed baryons are
composed of diquark and charm quark which are connected by a constant tension.
In a diquark picture, the quantum numbers $J^P$ of confirmed baryons are well
assigned. We give energy predictions for the first and second orbital
excitations. We see some correspondences with the experimental data. Meanwhile,
we have obtained diquark masses in the background of charm quark which satisfy
a splitting relation based on spin-spin interaction.
