Flavio Rojas, 48, was picked up last night on a highway 10 kilometres north of Guatemala City, the capital of a country where an estimated half of the population is below the national poverty line.
Police are investigating whether Rojas was transporting the money for an organised crime group.
Mexican drug organisations like the Zetas and the Sinaloa cartel have expanded their trafficking and money laundering operations in Guatemala in recent years, sometimes in combination with local groups.