An optical apparatus includes: at least one optical component configured to reflect first light that travels in a first direction toward a second direction, transmit second light that travels in the second direction, and generate leaked light traveling in the first direction, the leaked light including a first component transmitted in the first direction in the first light and a second component reflected toward the first direction in the second light; a first processing unit configured to absorb the leaked light, and reflect the leaked light in a predetermined direction; and at least one second processing unit configured to absorb the leaked light coming from the first processing unit.