To provide an imaging device with excellent starting performance.

An imaging device of this invention comprises: imaging means 10 having an imaging surface 12 to image an image by light flux; a lens tube 20 which has focus-adjustable optical systems L1, L2, and L3 and can change a state of the tube to a first state to focus on the imaging surface 12 by the focus adjustment of the optical systems L1, L2, and L3, and to a second state not to focus the image on the imaging surface 12; change means 25 to change the lens tube 20 from the second state to the first state at the starting of the imaging means 10; determination means 60 to determine whether the lens tube 20 is in the first state or the second state; and control means 50 which changes the lens tube 20 to the first state by the change means 25 when the state of the lens tube 20 at the starting of the imaging means 10 is determined to be in the second state, and maintains the first state when it is determined to be in the first state.