The director of the Honolulu Museum of Art, Stephan Jost, is leaving his post after five years to become director and CEO of the Art Gallery of Ontario, one of the largest art museums in North America.

“I’m slightly heartbroken about leaving Honolulu. I’m really going to miss the people — I made real and deep friendships there,” Jost said by phone Tuesday, speaking from Toronto, where he was meeting with Art Gallery of Ontario staff. “It’s a pretty exciting though,” he added. “Toronto is a huge city, and there’s an opportunity to really frame up a local conversation regarding art and culture.”

Family considerations also favored the move: Jost’s husband, Will Scott, was born in Toronto “and our 5-year-old daughter, Monique, is excited to live next to her grandparents,” he said.

His last day at the museum will be March 11 and he will begin work at the gallery in April, Jost said; the previous director, Matthew Teitelbaum, left in June to become director of the Museum of Fine Arts in Boston.

“We will certainly miss Stephan but we are completely thrilled for him,” said deputy director Allison Wong, 45, former director of the Contemporary Museum, who will serve as interim director at the Honolulu Museum of Art until Jost’s replacement is found. “Our house is in order, thanks to his leadership.”

Jost, 47, came to the museum as director in May 2011 with a reputation for reinvigorating education programs and community engagement as director of the Shelburne Museum in Vermont and, prior to that, at the Mills College Art Museum in Oakland, Calif. Under his leadership, the Honolulu Museum of Art has more than doubled its membership, which now stands at 13,000 — a historic high — with the majority of new members under the age of 40. In 2014, the museum had 299,500 visitors and participants in its education programs.

A decision to reduce the annual membership fee to $25 two years ago and give free admission to those under 18 years old sparked the “explosion” in numbers, Jost said. He also ramped up the Art After Dark events, which target younger people and draw an average of 2,000 attendees on the third Friday of every month. “I give a lot of credit to our social media team,” he said.

During his tenure, the museum has established a warm relationship with neighborhood schools and the Micronesian community: Every week, English-language learner students from Kaahumanu Elementary School visit the Art School, where McKinley High School teachers serve as assistant teachers. “It’s our kuleana and the right thing to do, to serve kids in our neighborhood,” Jost said. But, he added, there was also institutional self-interest. “Whoever engages the Micronesia community now will have a better relationship in 50 years (when they become prosperous). It’s a long-term game.”

The museum’s reputation in the art world has thrived, as well. Jost noted that its three-part Japanese Shunga erotic art show received “one of the top awards from the Association of Art Museum Curators.” Some of his other favorite exhibits were “the portraits of U.S. soldiers — a very moving touchstone, and Art Deco of Honolulu.”

Vi Loo, president of the museum’s board of trustees, praised Jost’s making the museum more accessible to the public and putting on a “great variety of exhibitions, from Georgia O’Keefe to Harajuku (Tokyo street fashion).” But she emphasized, “The most important and the thing that we are very grateful for is that he has reorganized the whole administrative structure so that each area, from finance to education, is well-organized and stabilized. We feel that now we have a very solid foundation for someone to come and take it to the next level.”