An observation assistance device of the present invention includes: an information storage unit that stores sample state information showing a sample state change, a type of sample, a type of fluorescent substance, and an observation condition in fluorescence observation performed on a predetermined sample, and under a predetermined observation condition; an input unit via which inputs the type of sample to be observed and the type of fluorescent substance to be used; an assistance-display generating unit that reads sample state information and an observation condition of fluorescence observation performed on the same type of sample as the type of sample input, using the same type of fluorescent substance as the type of fluorescent substance, and generates an assistance display showing the sample state information in relation to the two or more parameters included in the observation condition; and a display unit that displays the generated assistance display.