A signal observation includes an input unit that receives a first number of rows and a first number of columns; an observation unit that observes a volume of a target signal by using compressed sensing; a filter having a plurality of elements that are arranged in a matrix and that are capable of individually restricting the volume of the target signal to be transmitted to the observation unit; and a control unit that causes the observer to observe the volume of the target signal transmitted via the filter by changing states of the plurality of elements on the basis of a plurality of observation matrices each having a size determined on the basis of the received first number of rows and the received first number of columns.