Tom Selleck is apparently still very much a working actor -- to the point that he says he's worried about losing one of his properties now that his famous show is going off the air.

He made the startling revelation on CBS Sunday Morning this weekend -- where he was being interviewed about the fact 'Blue Bloods' had finally been canceled after 14 seasons ... where he served as the lead star for all them, playing the head honcho of the NYPD.

Now that his most consistent gig is getting the axe, Tom says he's not so sure he can afford his 63-acre ranch in Cali ... and while that might sound like a joke, homeboy ain't playing.

Take a listen for yourself ... Tom and the reporter are actually at his ranch in Ventura County -- which was once an avocado farm -- and they discuss what it'll mean with 'BB' ending.

To the journo's shock ... Tom says hopefully he can keep working enough to where he can hold onto the place, and when she asks if he's serious -- he tells her, you're GD right! TS keeps it 100 and tells her the reality of a consistent paycheck is always an issue, period.

He reflects on whether he's set for life -- and while he slightly hesitates, he eventually says, yeah, probably ... but in terms of being able to pay for a ranch of that size, probs not.

Bottom line ... Tom says he's very eager to find his next job, 'cause he's got bills to pay!