Mayor de Blasio on Wednesday admitted his wife’s $1 billion mental health plan is ailing — even as he discounted his own office’s report that found the agency lacking.

“I think it’s a mix,” Hizzoner told reporters when asked if he was concerned about ThriveNYC’s price tag compared to its outcomes. “As with every major initiative there’s going to be things that work better and things that work worse, things that need to be deepened, things that need to be reevaluated.”

The mayor noted that he scrapped Thrive’s costly “Mental Health Service Corps” program that sent social workers and psychologists to poor communities earlier this year because it “wasn’t working as planned.” But he said other facets of Thrive, like the hotline “NYC Well,” are “working extremely well.”

The mayor’s own management report found Tuesday that Thrive failed to meet a number of goals. Most glaring was the agency’s “mental health first aid” program that trained just 50,564 people how to detect depression last year, instead of the projected 72,000.

De Blasio claimed that the first aid program “is working unquestionably.”

“We need to speed up in terms of the number of people who get it,” he acknowledged. He said 100,000 people have been trained in mental health first aid since Thrive’s inception in 2015 and the goal is to train a total 250,000.

“I believe they’re going to hit that goal,” de Blasio said.

But then he dismissed those targets.

“If you guys are trying to report on things where traditional metrics and timelines tell you everything I can understand why it’s hard to understand some of what Thrive is doing,” de Blasio said. “The difference with Thrive is it’s trying to address an issue that doesn’t have an on and off switch,” he added. “Mental health, someone with a mental health condition, it doesn’t go away.”

Critics including City Comptroller Scott Stringer have questioned the purpose of Thrive, saying in May, “One of the basic questions we are trying to figure out is, what is Thrive?”

Expert DJ Jaffe of Mental Health Illness Policy Org. has called Thrive “a smoke-and-mirrors slush fund for the first lady.”