Exchange bias effect and crystal structure were studied in the Ni50Mn37.3Sn12.5−xGex (x = 0, 1, 2, 3) alloys. The lattice constant of austenite progressively decreases with Ge concentration. The martensite phase develops from a paramagnetic austenite. At the intermediate temperature range, between the Curie temperature of martensite and the martensite finish temperature, martensite shows superparamagnetic behavior. The exchange bias field increases from 17.6 mT (Ni50Mn37.5Sn12.5) to 20.4 mT (Ni50Mn37.5Sn9.5Ge3) with Ge content. Exchange bias effect originates in the coexistence between ferromagnetic and super ferromagnetic phases below the blocking temperature.