A surface plasmon resonance (SPR) detecting apparatus which controls the flow of fluid without using an additional pressure difference or pump is provided. The SPR detecting apparatus includes a detection chip, a fluid driving chip and an optical device. The fluid driving chip has a plurality of electrodes disposed on the flow space of the fluid. The angle between the liquid and a contact surface is changed by electrifying the electrodes, and the electrodes are turned on and turned off sequentially such that the droplets are controlled to move. The optical device is used to detect surface plasmon resonance phenomenon and to determine the interaction of the droplets and the detecting chip.