He could be charged with carrying a concealed weapon and with bringing a weapon on school grounds, The Detroit News reported Wednesday.
The student allegedly brought a loaded pistol to Eastover Elementary in Bloomfield Hills, north of Detroit, and showed it to another student, the newspaper said.
Bloomfield Township Police have petitioned Oakland County Probate Court for charges against the student, police Capt. Steve Cook said.
"This is a 9-year-old who made a terrible mistake, which will haunt him for the rest of his life," Cook said. "Do I want to throw the child away and lock up the key? No. We have to look at what is best for society and school and the child and parents at this time."
Police are investigating whether criminal charges could be brought against the boy's father, who lives in Wayne County where the student obtained the gun, the News reported.