To make an autofocus device of a linear motor system small in size and light in weight by realizing the position control of a focus lens without using a position sensor.

The autofocus device is equipped with the focus lens 1 forming an image with incident light on the light receiving surface of an imaging device, a linear motor constituted of a magnet 4 and a driving coil 3 and generating driving force in the direction of an optical axis 100 in the driving coil 3 in accordance with a driving current supplied to the driving coil 3, a lens holder 2 to which the focus lens 1 and the driving coil 3 are attached and which can move in the direction of the optical axis 100, holder springs 8 and 9 energizing the lens holder 2 in the direction of the optical axis 100, and endpoint detection means 10 and 11 detecting that the lens holder 2 is positioned at the endpoint of a movable area. By using the detection means 10 and 11, the driving current obtained when the lens holder reaches the endpoint of the movable range or it starts moving from the endpoint is discriminated.

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