Observation in which the properties of a detection element are utilized is performed. Provided is a detection device including: a detector that has a linear response characteristic, in which an output signal changes linearly, and a nonlinear response characteristic, in which the output signal changes nonlinearly, and that detects light from a sample and outputs the output signal in accordance with the intensity of the light; a light detection circuit that is capable of switching between a first amplification factor and a second amplification factor, the light detection circuit amplifying the output signal output from the detector based on the first amplification factor or the second amplification factor so as to generate a brightness signal; and an input unit with which a user is allowed to switch the amplification factor for the output signal to be used between the first amplification factor and the second amplification factor.