A detection method for detecting the presence or the amount of a detection target substance in a specimen by utilizing surface plasmon resonance using a detection chip including a channel for containing a liquid, the channel including a metal film with a reaction field which is exposed to the channel and a capturing body fixed to the metal film, wherein the metal film is capable of causing surface plasmon resonance, the detection method comprising: a step of controlling a liquid feeding unit to subject the inside of the channel to a blocking treatment by moving a blocking liquid containing a blocking agent in the channel to stir the blocking liquid within the channel, and wherein a flow rate of the blocking liquid in the channel is 1600 μL/min or more and 3300 μL/min or less and the concentration of the blocking agent in the blocking liquid is from 5% to 8% by mass; a step of controlling the liquid feeding unit to supply the specimen into the channel, causing the capturing body to capture the detection target substance; and a step of detecting (S60, S50') a light quantity of fluorescence (γ) emitted from the vicinity of a surface of the metal film located on a side of the channel or a light quantity of light reflected by the metal film located on a side of the channel by irradiating the metal film with light such that surface plasmon resonance occurs on the metal film while the detection target substance is bonded to the capturing body, wherein the step of supplying the specimen, causing the capturing body to capture the detection target substance, is performed following the step of performing the blocking treatment, with no step of cleaning the channel being performed between the step performing the blocking treatment and the step of causing the capturing body to capture the detection target substance. a step of controlling a liquid feeding unit to subject the inside of the channel to a blocking treatment by moving a blocking liquid containing a blocking agent in the channel to stir the blocking liquid within the channel, and wherein a flow rate of the blocking liquid in the channel is 1600 μL/min or more and 3300 μL/min or less and the concentration of the blocking agent in the blocking liquid is from 5% to 8% by mass; a step of controlling the liquid feeding unit to supply the specimen into the channel, causing the capturing body to capture the detection target substance; and a step of detecting (S60, S50') a light quantity of fluorescence (γ) emitted from the vicinity of a surface of the metal film located on a side of the channel or a light quantity of light reflected by the metal film located on a side of the channel by irradiating the metal film with light such that surface plasmon resonance occurs on the metal film while the detection target substance is bonded to the capturing body, wherein the step of supplying the specimen, causing the capturing body to capture the detection target substance, is performed following the step of performing the blocking treatment, with no step of cleaning the channel being performed between the step performing the blocking treatment and the step of causing the capturing body to capture the detection target substance.