A fluorescence reader , comprising: a base frame having an open part formed at the front thereof so that a diagnostic cartridge is inserted therein and having an inner space therein; an optical module disposed in the inner space of the base frame , and disposed to be positioned above the diagnostic cartridge inserted through the open part to irradiate a light to the diagnostic cartridge and to collect the fluorescent light emitted by the diagnostic cartridge ; a driving module for moving the optical module ; and a sensor module for sensing the insertion of the diagnostic cartridge and the position of the optical module , wherein the base frame further comprises a plate spring at least a part of which is protruded into a insertion space , wherein the plate spring is configured to put a pressure on at least a part of the diagnostic cartridge to fix the position of the diagnostic cartridge when the diagnostic cartridge is inserted into the insertion space , wherein the diagnostic cartridge comprises a measurement window extended in the direction of the lateral flow of a sample exposing the lateral flow of the sample, and wherein the optical module is configured to detect the start time of the lateral flow of the sample at the start point of the measurement window, to move to the end point of the measurement window after sensing the start time, and to detect the end time of the lateral flow of the sample at the end point of the measurement window, wherein the fluorescence reader is configured to calculate a rate of the lateral flow on the basis of the start time and the end time of the lateral flow. a base frame having an open part formed at the front thereof so that a diagnostic cartridge is inserted therein and having an inner space therein; an optical module disposed in the inner space of the base frame , and disposed to be positioned above the diagnostic cartridge inserted through the open part to irradiate a light to the diagnostic cartridge and to collect the fluorescent light emitted by the diagnostic cartridge ; a driving module for moving the optical module ; and a sensor module for sensing the insertion of the diagnostic cartridge and the position of the optical module , wherein the base frame further comprises a plate spring at least a part of which is protruded into a insertion space , wherein the plate spring is configured to put a pressure on at least a part of the diagnostic cartridge to fix the position of the diagnostic cartridge when the diagnostic cartridge is inserted into the insertion space , wherein the diagnostic cartridge comprises a measurement window extended in the direction of the lateral flow of a sample exposing the lateral flow of the sample, and wherein the optical module is configured to detect the start time of the lateral flow of the sample at the start point of the measurement window, to move to the end point of the measurement window after sensing the start time, and to detect the end time of the lateral flow of the sample at the end point of the measurement window, wherein the fluorescence reader is configured to calculate a rate of the lateral flow on the basis of the start time and the end time of the lateral flow. <EOS>