A variable-wavelength light source comprising: a first laser medium (M1) configured to amplify first light having a first wavelength band; a first total reflection mirror (K1A) and a first partial reflection mirror (K2) constituting a first optical resonator (R1) configured to cause the first light to optically resonate; a second laser medium (M2) configured to amplify second light having a second wavelength band; a second total reflection mirror (K1B) and a second partial reflection mirror (K2) constituting a second optical resonator configured to cause the second light to optically resonate; a first Fabry-Perot interference filter (FP1) having a pair of first mirrors, arranged at a first position which is a position between the first laser medium and the first partial reflection mirror on a first optical path of the first light and is a position between the second laser medium and the second partial reflection mirror on a second optical path of the second light, and configured to cause the first light and the second light to be transmitted and reflected selectively; a second Fabry-Perot interference filter (FP2) having a pair of second mirrors, arranged at a second position which is a position between the first laser medium and the first Fabry-Perot interference filter on the first optical path and is a position between the second laser medium and the first Fabry-Perot interference filter on the second optical path, and configured to cause the first light and the second light to be transmitted and reflected selectively; a first drive mechanism (A1) configured to operate one first mirror of the first Fabry-Perot interference filter and one second mirror of the second Fabry-Perot interference filter in conjunction with each other; and a second drive mechanism (A2) configured to operate the other second mirror of the second Fabry-Perot interference filter. a first laser medium (M1) configured to amplify first light having a first wavelength band; a first total reflection mirror (K1A) and a first partial reflection mirror (K2) constituting a first optical resonator (R1) configured to cause the first light to optically resonate; a second laser medium (M2) configured to amplify second light having a second wavelength band; a second total reflection mirror (K1B) and a second partial reflection mirror (K2) constituting a second optical resonator configured to cause the second light to optically resonate; a first Fabry-Perot interference filter (FP1) having a pair of first mirrors, arranged at a first position which is a position between the first laser medium and the first partial reflection mirror on a first optical path of the first light and is a position between the second laser medium and the second partial reflection mirror on a second optical path of the second light, and configured to cause the first light and the second light to be transmitted and reflected selectively; a second Fabry-Perot interference filter (FP2) having a pair of second mirrors, arranged at a second position which is a position between the first laser medium and the first Fabry-Perot interference filter on the first optical path and is a position between the second laser medium and the first Fabry-Perot interference filter on the second optical path, and configured to cause the first light and the second light to be transmitted and reflected selectively; a first drive mechanism (A1) configured to operate one first mirror of the first Fabry-Perot interference filter and one second mirror of the second Fabry-Perot interference filter in conjunction with each other; and a second drive mechanism (A2) configured to operate the other second mirror of the second Fabry-Perot interference filter. <EOS>