A coating apparatus capable of controlling a mixing ratio includes a spindle motor unit having a spindle with which an upper end portion of a mixing ratio control shaft is engaged, the upper end portion of the control shaft being moved on the spindle in accordance with rotation of the spindle; and a control unit for calculating the mixing ratio of a main coating agent and a hardening agent based on measured flow rates thereof and controlling the rotation of the spindle when the calculated mixing ratio of the main coating agent and the hardening agent falls outside a tolerance range of a presetmixing ratio. The mixing ratio of the main coating agent and the hardening agent is adjusted depending on the positions of the upper end portion of the mixing ratio control shaft on the spindle.