An imaging device comprising: an imaging lens moveable in a moveable range, in which the imaging lens is moveable upon a press of a release operation member, between an infinite side limit of the moveable range and a near side limit of the moveable range; an imaging unit which acquires image data based on an optical image of a subject received via the imaging lens, and an in-focus position estimating unit which estimates an in-focus position based on calculated focus position data; characterized by: a motion detector which detects a motion of the subject from image data sequentially acquired from the imaging unit; and a focus detector which calculates the focus position data based on image data acquired via the imaging lens while the imaging lens is driven in a drive range from a start position on the infinite side of the drive range to an end position on the near side of the drive range, the drive range being narrower than the moveable range, when the motion detector detects a motion of the subject; and wherein when the estimated in-focus position is not present in a sub-range of the moveable range outside the drive range, on the infinite side of the drive range but is in sub-range of the moveable range outside the drive range from the end position of the drive range to the near side limit of the moveable range, the imaging lens is adapted to start driving from the end position of the drive range to the near side limit of the moveable range, upon the press of the release operation member, and when the estimated in-focus position is not present in a sub-range of the moveable range outside the drive range, on the near side of the drive range but is in a sub-range of the moveable range outside the drive range from the start position of the drive range to the infinite side limit of the moveable range, the imaging lens is adapted to start driving towards the infinite side limit of the moveable range from the start position of the drive range, upon the press of the release operation member. an imaging lens moveable in a moveable range, in which the imaging lens is moveable upon a press of a release operation member, between an infinite side limit of the moveable range and a near side limit of the moveable range; an imaging unit which acquires image data based on an optical image of a subject received via the imaging lens, and an in-focus position estimating unit which estimates an in-focus position based on calculated focus position data; characterized by: a motion detector which detects a motion of the subject from image data sequentially acquired from the imaging unit; and a focus detector which calculates the focus position data based on image data acquired via the imaging lens while the imaging lens is driven in a drive range from a start position on the infinite side of the drive range to an end position on the near side of the drive range, the drive range being narrower than the moveable range, when the motion detector detects a motion of the subject; and wherein when the estimated in-focus position is not present in a sub-range of the moveable range outside the drive range, on the infinite side of the drive range but is in sub-range of the moveable range outside the drive range from the end position of the drive range to the near side limit of the moveable range, the imaging lens is adapted to start driving from the end position of the drive range to the near side limit of the moveable range, upon the press of the release operation member, and when the estimated in-focus position is not present in a sub-range of the moveable range outside the drive range, on the near side of the drive range but is in a sub-range of the moveable range outside the drive range from the start position of the drive range to the infinite side limit of the moveable range, the imaging lens is adapted to start driving towards the infinite side limit of the moveable range from the start position of the drive range, upon the press of the release operation member. a motion detector which detects a motion of the subject from image data sequentially acquired from the imaging unit; and a focus detector which calculates the focus position data based on image data acquired via the imaging lens while the imaging lens is driven in a drive range from a start position on the infinite side of the drive range to an end position on the near side of the drive range, the drive range being narrower than the moveable range, when the motion detector detects a motion of the subject; and wherein when the estimated in-focus position is not present in a sub-range of the moveable range outside the drive range, on the infinite side of the drive range but is in sub-range of the moveable range outside the drive range from the end position of the drive range to the near side limit of the moveable range, the imaging lens is adapted to start driving from the end position of the drive range to the near side limit of the moveable range, upon the press of the release operation member, and when the estimated in-focus position is not present in a sub-range of the moveable range outside the drive range, on the near side of the drive range but is in a sub-range of the moveable range outside the drive range from the start position of the drive range to the infinite side limit of the moveable range, the imaging lens is adapted to start driving towards the infinite side limit of the moveable range from the start position of the drive range, upon the press of the release operation member.