Martial made his first start since mid-January in Thursday's 2-2 draw with Sevilla in the first leg of the Europa League quarter-final, where he was taken off after the one-hour mark.
Fitness issues have held back the player, who has made 18 appearances this season but only 10 of those have been starts.
Asked if he can trust Martial to be part of the squad in the long term, Ten Hag told reporters: "It's difficult to say because the history shows different but I want him to be because he's a great player.
"He definitely has the qualities to play top football. When he's fit, our team plays better."
The Dutch manager described Martial as a versatile player but said he is at his best when leading the front line.
"I think he can play across the front. For me, he's best at centre forward, but he can play in the wide position as well," Ten Hag said.
With Marcus Rashford out with a groin injury, Martial is in line to start in Sunday's game away to Nottingham Forest.
United are fourth in the Premier League with 56 points, 17 points behind leaders Arsenal, who have played a game more.
