A light detection device, comprising: a Fabry-Perot interference filter having a first mirror and a second mirror, a distance therebetween being variable, and provided with a light transmission region on a predetermined line, the light transmission region configured to transmit light corresponding to the distance between the first mirror and the second mirror; a light detector arranged on a first side of the Fabry-Perot interference filter on the line, the light detector configured to detect light transmitted through the light transmission region; a package having an opening positioned on a second side of the Fabry-Perot interference filter on the line, the package configured to accommodate the Fabry-Perot interference filter and the light detector; and a light transmitting unit arranged on an inner surface of the package so as to close the opening and including a band pass filter configured to transmit light incident on the light transmission region, wherein, when viewed from a direction parallel to the line, an outer edge of the Fabry-Perot interference filter is positioned outside an outer edge of the opening, and an outer edge of the light transmitting unit is positioned outside the outer edge of the Fabry-Perot interference filter; wherein the package is a CAN package having a stem and a cap, the cap is integrally formed by a side wall and a top wall, and the top wall includes the opening; and wherein the light transmitting unit further includes a light transmitting member provided with the band pass filter, and the light transmitting member arranged on the inner surface of the package extends to an inner surface of the side wall. a Fabry-Perot interference filter having a first mirror and a second mirror, a distance therebetween being variable, and provided with a light transmission region on a predetermined line, the light transmission region configured to transmit light corresponding to the distance between the first mirror and the second mirror; a light detector arranged on a first side of the Fabry-Perot interference filter on the line, the light detector configured to detect light transmitted through the light transmission region; a package having an opening positioned on a second side of the Fabry-Perot interference filter on the line, the package configured to accommodate the Fabry-Perot interference filter and the light detector; and a light transmitting unit arranged on an inner surface of the package so as to close the opening and including a band pass filter configured to transmit light incident on the light transmission region, wherein, when viewed from a direction parallel to the line, an outer edge of the Fabry-Perot interference filter is positioned outside an outer edge of the opening, and an outer edge of the light transmitting unit is positioned outside the outer edge of the Fabry-Perot interference filter; wherein the package is a CAN package having a stem and a cap, the cap is integrally formed by a side wall and a top wall, and the top wall includes the opening; and wherein the light transmitting unit further includes a light transmitting member provided with the band pass filter, and the light transmitting member arranged on the inner surface of the package extends to an inner surface of the side wall.