Rutchada Suriyakul na Ayutya, director-general of the Department of National Parks, Wildlife and Plant Conservation, was appointed in February.
He managed efforts to protect the kingdom’s environment and endangered animals, overseeing more than 150 national parks.
“The officials have arrested him while the money was exchanged, so the evidence was quite clear,” said Jaroonkiat Pankaew, chief of the Anti-Corruption Division.
Police searched Rutchada’s office in the capital, Bangkok, after he was detained and found roughly B5mn in cash, Jaroonkiat said.
Rutchada has denied all the charges.
Images shared by Thai police showed stacks of money, with brown envelopes underneath.
“Officials have collected B98,000 as evidence,” Jaroonkiat said.
The National Anti-Corruption Commission (NACC) said in a statement Rutchada had “abused his power by receiving money from his inferiors, in exchange for maintaining their positions”.
The NACC alleged Rutchada’s subordinates had been forced to pay a monthly tithe, in addition to a one-off payment of up to B300,000, or face relocation to “remote places far away from their hometown”.