The superconducting phase transitions of quasi-one-dimensional compound (V 6 S 8 , InV 6 S 8 , TlV 6 S 8 ) were studied by the measurement of AC magnetic susceptibility χ'. In the sintered sample, the χ' began to decrease monotonously at T C 1 . On the other hand, the χ' of powdered sample decreased stepwise, and was characterized by two transition temperatures T C 1 and T C 2 (T C 1 >T C 2 ). Under the magnetic field, T C 2 shifted to the lower temperature, while the shift of T C 1 was negligibly small. The T C 1 is considered to be the transition temperature in the grains, and T C 2 is the inter-grain transition temperature.