A microscope (1, 100), comprising: a sample placement part having a placement surface on which to place a sample and a bottom face opposite to the placement surface; an observation lens for receiving fluorescence from the sample; and an optical unit for generating sheet light traveling in a direction parallel to an observation plane of the observation lens, the sheet light entering the sample placement part from the bottom face and passing through the sample placement part to irradiate the sample, the fluorescence passing through the sample placement part toward the bottom face to be received by the observation lens the microscope further comprising a fluid holding device for holding fluid between the observation lens and the sample placement part, wherein the fluid holding device comprises: a connection section for connection to the observation lens; an end face so designed as to face the bottom face; a transmission window through which the sheet light enters the sample placement part; and a fluid holding section for holding the fluid inside itself; and wherein in a state where the fluid holding device is connected to the observation lens, the end face is substantially parallel to the bottom face, the sheet light passes through the transmission window and then through the fluid holding section to irradiate the sample, and the fluorescence passes through the fluid holding section to be received by the observation lens. a sample placement part having a placement surface on which to place a sample and a bottom face opposite to the placement surface; an observation lens for receiving fluorescence from the sample; and an optical unit for generating sheet light traveling in a direction parallel to an observation plane of the observation lens, the sheet light entering the sample placement part from the bottom face and passing through the sample placement part to irradiate the sample, the fluorescence passing through the sample placement part toward the bottom face to be received by the observation lens the microscope further comprising a fluid holding device for holding fluid between the observation lens and the sample placement part, wherein the fluid holding device comprises: a connection section for connection to the observation lens; an end face so designed as to face the bottom face; a transmission window through which the sheet light enters the sample placement part; and a fluid holding section for holding the fluid inside itself; and wherein in a state where the fluid holding device is connected to the observation lens, the end face is substantially parallel to the bottom face, the sheet light passes through the transmission window and then through the fluid holding section to irradiate the sample, and the fluorescence passes through the fluid holding section to be received by the observation lens. a connection section for connection to the observation lens; an end face so designed as to face the bottom face; a transmission window through which the sheet light enters the sample placement part; and a fluid holding section for holding the fluid inside itself; and wherein in a state where the fluid holding device is connected to the observation lens, the end face is substantially parallel to the bottom face, the sheet light passes through the transmission window and then through the fluid holding section to irradiate the sample, and the fluorescence passes through the fluid holding section to be received by the observation lens.