Finance Chief Greg Gadel quit Thursday after eight years at the company.
The Minneapolis-based restaurant chain said it would search for a replacement. Buca shares fell 5% in postclose trading.
"Greg has accepted the position of president of a local restaurant company, Parasole Restaurant Holdings," said CEO Wally Doolin. "Although Greg will be missed, I'm supportive of the opportunity for him and wish him the best in his new position."
Shares of Buca, which operates the Buca di Beppo and Vinny T's of Boston chains, slipped 32 cents to $5.81.