The Immigration and Checkpoints Authority said in a Facebook post Thursday that its officers apprehended the man following a routine check while he was passing through terminal 1.
They found the undeclared cash on him and handed him over to police for further investigation.
The Corruption, Drug Trafficking and Other Serious Crimes Act allows a Singaporean citizen or foreign tourist to carry up to S$20,000 into the island-state without declaration.
Any violation could result in a fine of up to S$50,000 or imprisonment of up to three years.