We report on the first detection of maser emission in the J=11-10, J=14-13 and J=15-14 transitions of the v=0 vibrational state of SiS toward the C-rich star IRC+10216. These masers seem to be produced in the very inhomogeneous region between the star and the inner dust formation zone, placed at 5-7 R*, with expansion velocities below 10 km/s. We interpret the pumping mechanism as due to overlaps between v=1-0 ro-vibrational lines of SiS and mid-IR lines of C2H2, HCN and their 13C isotopologues. The large number of overlaps found suggests the existence of strong masers for high-J v=0 and v=1 SiS transitions, located in the submillimeter range. In addition, it could be possible to find several rotational lines of the SiS isotopologues displaying maser emission.We want to thank the IRAM staff, M. J. Richter (NSF grant AST-0307497), J. H. Lacy (NSF grant AST-0205518), and collaborators for the mid-infrared observations, and Spanish MEC for funding support through grant ESP2004-665, AYA2003-2785, and "Comunidad de Madrid" Government under PRICIT project S-0505/ESP-0237 (ASTROCAM). This study is supported in part by the European Community’s human potential Programme under contract MCRTN-CT-2004- 51230, Molecular Universe.Peer reviewed