The present invention provides a detector and an emission tomography device including the detector. The detector comprises: a scintillation crystal array comprising a plurality of scintillation crystals； and a photo sensor array, coupled to an end surface of the scintillation crystal array and comprising multiple photo sensors. At least one of the multiple photo sensors is coupled to a plurality of the scintillation crystals respectively. Surfaces of the plurality of the scintillation crystals not coupled to the photo sensor array are each provided with a light-reflecting layer, and a light-transmitting window is disposed in the light-reflecting layer on a surface among the surfaces adjacent to a scintillation crystal coupled to an adjacent photo sensor. The detector has DOI decoding capability. No mutual interference occurs during DOI decoding, and decoding is more accurate. Moreover, with the number of photo sensor arrays being the same, the decoding capability for the scintillation crystals is significantly improved. With the number of photo sensor arrays being the same, the size of the photo sensor array and the number of channels of a readout circuit of the photo sensors of the present invention can be reduced by three-quarters to eight-ninths.
