Three or more devices can be connected to a microscope and can be used simultaneously. Provided is a microscope connecting unit including a microscope connection port that is connected to a microscope used to observe a sample; three or more unit connection ports to which a stimulating unit that irradiates the sample with light or a confocal observation unit or an image capturing unit that detects light generated at the sample is connectable; and two or more light-path combining units that are disposed between the microscope connecting port and the unit connection ports and that combine light paths optically connecting the microscope with the confocal observation unit, the stimulating unit, and the image capturing unit.