A fluorescence detection device comprising: a reference stand which has a plate shape; a scanning module that includes a light source which emits excitation light for excitation of fluorescence and a detection optical system which detects fluorescence emitted from a detection target based on the irradiation of the excitation light, and scans two-dimensionally in a first scanning direction and a second scanning direction substantially orthogonal to the first scanning direction; an upper operation support section which supports the scanning module to allow the scanning module to perform a reciprocating operation in the second scanning direction and in a plane direction of the reference stand; and a lower operation support section which is disposed on the reference stand and supports the upper operation support section to allow the upper operation support section to perform a reciprocating operation in the first scanning direction and in a plane direction of the reference stand, characterised in that the reference stand has an opening and the upper operation support section includes a belt for causing the scanning module to perform a reciprocating operation in the second scanning direction, a belt driving section which drives the belt, and a belt pulling-down section which causes the belt to pass through the opening of the reference stand and to be pulled down from a scanning module side to a side opposite to the scanning module side, wherein the belt driving section is positioned on the side opposite to the scanning module with respect to a surface of the reference stand and disposed in the belt pulling-down section. a reference stand which has a plate shape; a scanning module that includes a light source which emits excitation light for excitation of fluorescence and a detection optical system which detects fluorescence emitted from a detection target based on the irradiation of the excitation light, and scans two-dimensionally in a first scanning direction and a second scanning direction substantially orthogonal to the first scanning direction; an upper operation support section which supports the scanning module to allow the scanning module to perform a reciprocating operation in the second scanning direction and in a plane direction of the reference stand; and a lower operation support section which is disposed on the reference stand and supports the upper operation support section to allow the upper operation support section to perform a reciprocating operation in the first scanning direction and in a plane direction of the reference stand, characterised in that the reference stand has an opening and the upper operation support section includes a belt for causing the scanning module to perform a reciprocating operation in the second scanning direction, a belt driving section which drives the belt, and a belt pulling-down section which causes the belt to pass through the opening of the reference stand and to be pulled down from a scanning module side to a side opposite to the scanning module side, wherein the belt driving section is positioned on the side opposite to the scanning module with respect to a surface of the reference stand and disposed in the belt pulling-down section.