We report here on the discovery of the superconductivity of a new ternary compound LaRh2Ga2, which possesses a CaBe2Ge2-type structure. Electrical resistivity and magnetic susceptibility measurements reveal that LaRh2Ga2 undergoes a superconducting transition at 3.7 K and exhibits type-II superconductivity. The T-linear behavior of the upper critical field is likely induced by the two-gap superconducting state because of its structural features (i.e., its noncentrosymmetric structure). A transition at T-c of specific heat suggested that the LaRh2Ga2 is a weak electron-phonon-mediated superconductor. Comparison with a related superconductor demonstrates that there is an important factor other than electron-phonon coupling strength that induces higher T-c in the LaTM2Ga2 system with a noncentrosymmetric CaBe2Ge2-type structure.