Advocaat said that while PSV would miss such an influential player, it is necessary for Strootman's development that he moves - particularly into English football.
A host of Premier League clubs are said to be interested in the 23-year-old's signature, including Liverpool and Tottenham who have reportedly been monitoring him for the past two seasons.
"For PSV it would be good if he stays, but for Strootman himself it's better to leave," Advocaat told De Telegraaf.
"He's the reserve captain of the Dutch national squad and PSV will make another step next season.
"This guy fits everywhere. He's a fantastic player because he knows exactly what his qualities are."Strootman has scored five goals and assisted 11 more in the Eredivisie this season, making him the joint-fifth highest assist-maker in Europe.
"[He would be good for] Liverpool and Tottenham Hotspur, but I think he's also good enough for Manchester City and Manchester United," Advocaat continued.
"Strootman is nothing less than Gareth Barry. He's a very useful player for every team. Especially when he's surrounded by better players."