An image pickup device that is provided at a distal end portion of an insertion unit of an endoscope having a longitudinal axis, includes: a first lens barrel that houses a first optical system; a second lens barrel that is disposed on a proximal end side of the first lens barrel, houses a second optical system on which light having passed through the first optical system is to be incident, and includes a second lens barrel-distal end portion that is a distal end portion having a diameter smaller than a diameter of a first lens barrel-proximal end portion which is a proximal end portion of the first lens barrel; a sliding part that is provided around an outer peripheral surface of the second lens barrel-distal end portion and that is in contact with the first lens barrel-proximal end portion; and a pressing member that is externally fitted over the sliding part from the first lens barrel-proximal end portion. The pressing member includes a pressing member-inner peripheral surface that is in contact with both an outer peripheral surface of the first lens barrel-proximal end portion and an outer peripheral surface of the sliding part, and a movement restricting portion that restricts a movement of the sliding part in an axial direction of the longitudinal axis between the first lens barrel-proximal end portion and the movement restricting portion.