Police said the man, 62-year-old Francis T. Wright, was shopping for sofas on Monday when the gun fell from his pocket.
Not long after, a 6-year-old boy found it and fired the gun.
No one was hurt, but the shots startled customers.
Ikea issued an apology and said its stores have a no-weapons policy.
The man who owns the gun has been charged with one count of criminal recklessness.
The Associated Press contributed to this report.