A connection optimization device that optimizes connections between a plurality of FXC switches for switching connections of optical fibers includes a optimization unit for receiving, as inputs, a number k of FXC switches, a number n of sending/receiving ports, and a connection probability matrix C of the sending/receiving ports and swapping rows and columns of the connection probability matrix C so as to maximize an expected value D in which a connection probability using a short path connecting between the sending/receiving ports connected in the same FXC switch becomes the largest, and a swapping port information output unit for outputting difference information between the connection probability matrix C and the optimization matrix C* in which the rows and the columns are swapped by the optimization unit.