Just rechecked, he was injured and has not fully recovered yet.
Borussia Dortmund forward Reus, who missed the 2014 World Cup through injury, is currently struggling with a groin problem and the 27-year-old will not travel to France.
"Reus can only run straight run now," Low told a news conference on Tuesday. "He could do no more in training. The medical staff was sceptical that he would be fully fit.
"It's a bitter decision for him and us. He would be a major gain for our team if he was fit."
Full squad -
Goalkeepers: Manuel Neuer (Bayern Munich), Bernd Leno (Bayer Leverkusen), Marc-Andre ter Stegen (Barcelona)
Defenders: Jerome Boateng (Bayern Munich), Mats Hummels (Borussia Dortmund), Emre Can (Liverpool), Jonas Hector (Cologne), Benedikt Howedes (Schalke), Shkodran Mustafi (Valencia), Antonio Rudiger (Roma)
Midfielders: Mario Gotze (Bayern Munich), Mesut Ozil (Arsenal), Sami Khedira (Juventus), Toni Kroos (Real Madrid), Julian Draxler (Wolfsburg), Joshua Kimmich (Bayern Munich), Bastian Schweinsteiger (Manchester United), Julian Weigl (Borussia Dortmund)
Forwards: Thomas Muller (Bayern Munich), Andre Schurrle (Wolfsburg), Lukas Podolski (Galatasaray), Mario Gomez (Besiktas), Leroy Sane (Schalke)