Police are on the hunt for a rampant subway masturbator who was allegedly caught fondling himself in two separate incidents last week.

Robert Mannis, 61, was inside the Herald Square subway station Oct. 2 when a 27-year-old woman witnessed him fondling himself on the platform around 6:30 p.m., according to police.

The next day, Oct. 3, Mannis was on an E train at about 9:30 when a 27-year-old woman allegedly spotted him masturbating as he stared at her.

The second victim took a picture of Mannis with her cellphone before he exited the train at the Lexington Avenue/53 Street station.

Mannis has an extensive arrest history for similar incidents, police sources said.

In March, Mannis was busted three times for exposing himself in the subway.