A spectroscope comprising: a package provided with a light entrance part ; a support part opposing the light entrance part in the package ; a plurality of lead pins penetrating through the support part ; a light detection unit supported on the support part within the package ; and a spectroscopic unit supported on the support part within the package so as to be arranged on the support part side of the light detection unit ; wherein the light detection unit has a light transmission part for transmitting therethrough light incident thereon from the light entrance part ; wherein the spectroscopic unit has a spectroscopic part for spectrally resolving the light transmitted through the light transmission part while reflecting the light to a light detection part of the light detection unit ; wherein the lead pins are electrically connected to the light detection part ; and characterized in that the light detection unit is provided at a distance from the spectroscopic unit so as to form a space through which the light transmitted through the light transmission part and reflected by the spectroscopic part is transmitted, in that the spectroscopic unit is secured to the support part without the light detection unit intervening in the connection between the spectroscopic unit and the support part , and in that the lead pins are fitted into fitting parts of the light detection unit , so that, through the plurality of lead pins , the light transmission part formed in the light detection unit is positioned with respect to the light entrance part provided with the package at least in a direction perpendicular to the direction in which the light entrance part and the support part oppose each other. a package provided with a light entrance part ; a support part opposing the light entrance part in the package ; a plurality of lead pins penetrating through the support part ; a light detection unit supported on the support part within the package ; and a spectroscopic unit supported on the support part within the package so as to be arranged on the support part side of the light detection unit ; wherein the light detection unit has a light transmission part for transmitting therethrough light incident thereon from the light entrance part ; wherein the spectroscopic unit has a spectroscopic part for spectrally resolving the light transmitted through the light transmission part while reflecting the light to a light detection part of the light detection unit ; wherein the lead pins are electrically connected to the light detection part ; and characterized in that the light detection unit is provided at a distance from the spectroscopic unit so as to form a space through which the light transmitted through the light transmission part and reflected by the spectroscopic part is transmitted, in that the spectroscopic unit is secured to the support part without the light detection unit intervening in the connection between the spectroscopic unit and the support part , and in that the lead pins are fitted into fitting parts of the light detection unit , so that, through the plurality of lead pins , the light transmission part formed in the light detection unit is positioned with respect to the light entrance part provided with the package at least in a direction perpendicular to the direction in which the light entrance part and the support part oppose each other. <EOS>