About one quintal of the narcotic was seized from near Dudhnoi town, about 110 km from here, after police intercepted the bus which was on its way from Guwahati to Dhubri.
The seized ganja is worth about Rs 5 lakh in the market, the police said.
Five persons who were carrying the ganja, which was meant to be later smuggled out of the state, were arrested from the bus, the police said adding they were being interrogated.