A Staten Island construction boss’ backpack stuffed with $40,000 in cash was snatched from his car while he was at a Brooklyn business meeting — and he thinks it may have been an inside job.

James Valouch, head of Black Square Builders, parked his 2014 Jeep near a job site in Brooklyn Heights earlier this month when a hooded thief used a four-way lug wrench to break into his vehicle, according to police.

“This guy seemed to be casing me,” Valouch, 52, told The Post.

“He was walking down the block — seemed to have gone around a couple of times. When he walked up that block with a crowbar in his hand, he was heading my way.”

Inside the vehicle, the construction boss left behind the backpack stuffed with bundles of cash to be doled out to temporary workers for payday — in addition to various project-related costs throughout the day.

“I don’t drive around with that kind of cash everyday,” Valouch said. “It was just a perfect storm of circumstances.”

Just minutes after the construction honcho parked his car, a 77-year-old witness heard an unusual popping sound outside her apartment.

The woman — who declined to give her name — watched as the suspect tried to open the door.

“Wait a minute, what are you doing!?” she yelled at the hooded man.

She then watched the suspect bust into the Jeep where the bag of cash was stashed.

“He had a big crowbar — and he swung it,” the woman told The Post. “He was breaking the window. I said ‘Stop it, stop that.’ Then I went running to call the police.”

The suspect could be seen in surveillance footage swiping the backpack from the front seat around 1 p.m. before fleeing on foot, police said.

Valouch believes that the thief was familiar with his business affairs, possibly through a former employee.

In addition to the piles of cash, the suspect made off with Valouch’s wallet and checkbooks, as well as his notary stamp, he said.

“It stinks. It’s more than the money,” Valouch said.

As far as the getting the cash back, Valouch said he’d rather have his personal item

“Keep the cash,” he said about the suspect. “But if you can find a way to get me back my stuff, please do.”

Additional reporting by Alex Taylor and Shari Logan