An incorrigible subway perv racked up his 36th arrest last week for allegedly groping a female straphanger — just over a month after completing an 11-year prison stint for similar crimes, authorities said Monday.

Freddie Johnson, 61, allegedly ground his groin against a 27-year-old woman’s rear aboard a 5 train rumbling northbound near Lower Manhattan’s Fulton Street on Dec. 11, according to cops.

The skeeved straphanger tried to move elsewhere in the car, but Johnson allegedly followed her, again pressed himself against her and grabbed her rear, police said.

Johnson was busted by cops at Grand Central a short time later, marking his 55th lifetime arrest, and 36th for a sexual attack against a woman in the subway system — but the first since his Nov. 6 release from custody after serving 11 years for a persistent sexual abuse conviction, according to police sources and prison records.

Johnson — whose record stretches back to the 1980s and has been chronicled in The Post before — was highlighted by transit cops at Monday’s monthly MTA board meeting, and comes amid a push to ban repeat subway perverts from the system for life.

“He has 55 prior arrests, approximately 50 in transit, with 36 of them being sex-related,” said Chief Vincent Coogan of the NYPD’s 2nd Transit District. “If we see them [repeat offenders] in the transit system, we can’t arrest them, but we can notify parole.

“They can take their parole away and put them back in [prison], but we can’t arrest them based on just being in the system.”

Word of Johnson’s arrest renewed the conversation about how the system can deal with repeat sexual-offenders.

“Proposed legislation is all well and good, but time goes by and things happen, right?” said Linda Lacewell, a member of the board appointed by Gov. Andrew Cuomo, during the presentation.

“I think that we need to be in communication with whatever agencies make recommendations to the court when someone is being sentenced or when someone is being released, so that we can directly communicate the facts and circumstances,” continued Lacewell.

Legislative efforts to bar known pervs from riding the rails have been made in fits and starts over the years, but have never gotten on the books, with concerns about depriving even the worst recidivists of access to public transit proving a stumbling block.

At a Dec. 12 appearance in Manhattan Criminal Court, Johnson was charged again with persistent sexual abuse and forcible touching, and was held in lieu of $150,000 bond or $50,000 cash.

He is due back in court on Tuesday.