An optical device includes: a base having first and second ends in first and second directions, respectively, and extends in the first direction; an optical module having a head adjacent to the base and is positioned close to the second end and a neck protruding from the head and is thinner than the head; a substrate attached on the base arranged with the head; and a pressing member having a first fixing portion fixed to the base, a second fixing portion fixed to the base, a first extension portion extending from the first fixing portion, a second extension portion extending from the second fixing portion, and a pressing portion provided in at least one of the first and the second extension portions and presses the head against the base.