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 (L), 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 (L), 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 (L), 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 (L), 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 (L), 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 (L), 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 (L), 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 (L), 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 . <EOS>