A solid phase extraction method with a micro device having a dam-forming portion including a dam, wherein each of the dam-forming portion and the dam has a circular cross section with respect to a central axis of the micro device, the method comprising the steps of: (i) injecting a solvent and a filler into the micro device to move to the dam-forming portion, wherein the filler is filled in the form of a disk with respect to the central axis in the dam-forming portion, the dam being adjusted to allow only the solvent to flow through but the filler not to pass through and, thereby adsorbing a material to be separated onto the filler in the dam-forming portion; and (ii) extracting the adsorbed material to be separated from the filler, wherein in one step of the steps (i) and (ii), the micro device is rotated about the central axis of the micro device, and the rotation of the micro device is performed at an angular velocity defined by Equation 1 below. ω > g r cos 90 ° − φ wherein, ω is a rotational angular velocity of the micro device in units of s -1, g is an acceleration of gravity in units of m s -2, r is a radius of the dam-forming portion or a radius of the dam of the micro device in units of m, φ is an angle at which the central axis of the micro device is inclined from an axis of a horizontal plane, and φ is in the range of 0° <φ <90°. (i) injecting a solvent and a filler into the micro device to move to the dam-forming portion, wherein the filler is filled in the form of a disk with respect to the central axis in the dam-forming portion, the dam being adjusted to allow only the solvent to flow through but the filler not to pass through and, thereby adsorbing a material to be separated onto the filler in the dam-forming portion; and (ii) extracting the adsorbed material to be separated from the filler, wherein in one step of the steps (i) and (ii), the micro device is rotated about the central axis of the micro device, and the rotation of the micro device is performed at an angular velocity defined by Equation 1 below. ω > g r cos 90 ° − φ wherein, ω is a rotational angular velocity of the micro device in units of s -1, g is an acceleration of gravity in units of m s -2, r is a radius of the dam-forming portion or a radius of the dam of the micro device in units of m, φ is an angle at which the central axis of the micro device is inclined from an axis of a horizontal plane, and φ is in the range of 0° <φ <90°. wherein in one step of the steps (i) and (ii), the micro device is rotated about the central axis of the micro device, and the rotation of the micro device is performed at an angular velocity defined by Equation 1 below. ω > g r cos 90 ° − φ wherein, ω is a rotational angular velocity of the micro device in units of s -1, g is an acceleration of gravity in units of m s -2, r is a radius of the dam-forming portion or a radius of the dam of the micro device in units of m, φ is an angle at which the central axis of the micro device is inclined from an axis of a horizontal plane, and φ is in the range of 0° <φ <90°. ω is a rotational angular velocity of the micro device in units of s -1, g is an acceleration of gravity in units of m s -2, r is a radius of the dam-forming portion or a radius of the dam of the micro device in units of m, φ is an angle at which the central axis of the micro device is inclined from an axis of a horizontal plane, and φ is in the range of 0° <φ <90°.