Aguilar, 59, told police in the Fairview area of Quezon City, the Philippines' largest city, he discovered the money missing Sunday, police said. He said it had been stored inside a vault in his master bedroom that he last opened a week ago, they said.
Police Superintendent Virgilio Fabian said the money was missing but a gun left near the vault was untouched, the Philippine Daily Inquirer reported.
Fabian said the vault was undamaged and its combination lock and key hole appeared intact.
"Mr. Aguilar believes it is an inside job," Fabian was quoted by the Inquirer as saying.
Aguilar believes he knows the thief but would not divulge the person's name, police said.
Aguilar is known for the popular song "Anak" and for "Bayan Ko," the unofficial opposition anthem during the Philippines' 1986 revolution against the regime of President Ferdinand Marcos.