A spokesman from the force said detectives started investigating after learning that the police constable, 28, was allegedly involved in the operation of an illegal gambling centre.
The officer was among three people, aged between 23 and 29, who were detained for allegedly operating a gambling establishment after a raid at an industrial building in Kwun Tong in the early hours of Saturday.
Another 57 people, aged between 18 and 54, in the premises were arrested on suspicion of gambling.
All were also given a fixed penalty ticket for flouting social distancing rules, a police spokesman said.
During the operation, officers seized HK$480,000 in cash, HK$120,000 worth of chips and other items.
The police also said the officer had been released on bail pending investigation.