A method of manufacturing a spectroscopic sensor 1 comprises a first step of forming a cavity layer 21 by nanoimprinting on a handle substrate; a second step of forming a first mirror layer 22 on the cavity layer 21 after the first step; a third step of joining a light-transmitting substrate 3 onto the first mirror layer 22 after the second step; a fourth step of removing the handle substrate from the cavity layer 21 after the third step; a fifth step of forming a second mirror layer 23 on the cavity layer 21 without the handle substrate after the fourth step; and a sixth step of joining the light detection substrate 4 onto the second mirror layer 23 after the fifth step.