An object of the present invention is to suppress variations in measurement values when measuring a specific binding reaction between a physiologically active substance and a tested substance using a surface plasmon resonance measurement device, so that binding detection data with high reliability is obtained. The present invention provides a method for measuring a change in surface plasmon resonance, which comprises: using a surface plasmon resonance measurement device comprising a flow channel system having a cell formed on a metal film and a light-detecting means for detecting the state of surface plasmon resonance by measuring the intensity of a light beam totally reflected on the metal film; and exchanging the liquid contained in the above flow channel system, wherein a major axis of the metal film is 0.1 μm or more and 100 μm or less; a molecule interacting with an analyzed molecule is immobilized on the surface of the metal film; the distance between metal films is 200 μm or more and 10 mm or less; and the molecule interacting with the analyzed molecule is not immobilized on any parts other than the metal films.