We succeeded in synthesizing a novel cuprate compound, [Cu-2(CO3)(2)(bpp)(2.5)].5.5H(2)O (1) (bpp: 1,3-bis(4-pyridyl)propane). Its structural determination reveals that 1 has a ladder-like configuration formed by the alternate stacking of two Cu2+ ions and a CO32- ion, each of which is linked by a bpp molecule. The results of magnetic susceptibility measurements indicate that the obtained magnetic susceptibility curve can be reproduced faithfully by a magnetically isolated spin ladder-based model with the ladder-rung magnetic interaction, J(rung)/k(B) = 366 K and the ladder-leg interaction, J(leg)/k(B) = 11.5 K, where J is defined as being positive (negative) for antiferro-magnetic (ferromagnetic) interactions.