A photodiode array module comprising: a first semiconductor substrate formed with a plurality of amplifiers, made of a first semiconductor material; and a second semiconductor substrate adhered to the first semiconductor substrate, made of a second semiconductor material different from the first semiconductor material, wherein light is incident on the photodiode array module from the second semiconductor substrate side, wherein the first semiconductor substrate has a first photodiode array, the second semiconductor substrate has a second photodiode array at a side of a surface opposed to the first semiconductor substrate, a first group of a plurality of the amplifiers, wherein said amplifiers are respectively electrically connected to respective photodiodes of the first photodiode array via a first wiring group provided on the first semiconductor substrate, a second group of a plurality of the amplifiers, wherein said amplifiers are respectively electrically connected to respective photodiodes of the second photodiode array via a second wiring group provided on the first semiconductor substrate and bumps respectively provided on the second wiring group, in the second semiconductor substrate, an end portion close to the first photodiode array side has a stepped portion, the stepped portion has: a first side surface and a second side surface along a thickness direction of the second semiconductor substrate; and a terrace surface located at a boundary between the first side surface and the second side surface and opposed to the first semiconductor substrate, each of the photodiodes composing the second photodiode array includes: a semiconductor region of a first conductivity type; and a pixel region of a second conductivity type located at a surface layer side of a surface of the second semiconductor substrate opposed to the first semiconductor substrate, a depth of the terrace surface from an opposing surface of the second semiconductor substrate to the first semiconductor substrate is deeper than a depth of the pixel region of the second photodiode array, the first side surface is closer to the first semiconductor substrate than the second side surface, and a crystal defect density in the first side surface is lower than a crystal defect density in the second side surface. a first semiconductor substrate formed with a plurality of amplifiers, made of a first semiconductor material; and a second semiconductor substrate adhered to the first semiconductor substrate, made of a second semiconductor material different from the first semiconductor material, wherein light is incident on the photodiode array module from the second semiconductor substrate side, wherein the first semiconductor substrate has a first photodiode array, the second semiconductor substrate has a second photodiode array at a side of a surface opposed to the first semiconductor substrate, a first group of a plurality of the amplifiers, wherein said amplifiers are respectively electrically connected to respective photodiodes of the first photodiode array via a first wiring group provided on the first semiconductor substrate, a second group of a plurality of the amplifiers, wherein said amplifiers are respectively electrically connected to respective photodiodes of the second photodiode array via a second wiring group provided on the first semiconductor substrate and bumps respectively provided on the second wiring group, in the second semiconductor substrate, an end portion close to the first photodiode array side has a stepped portion, the stepped portion has: a first side surface and a second side surface along a thickness direction of the second semiconductor substrate; and a terrace surface located at a boundary between the first side surface and the second side surface and opposed to the first semiconductor substrate, a first side surface and a second side surface along a thickness direction of the second semiconductor substrate; and a terrace surface located at a boundary between the first side surface and the second side surface and opposed to the first semiconductor substrate, each of the photodiodes composing the second photodiode array includes: a semiconductor region of a first conductivity type; and a pixel region of a second conductivity type located at a surface layer side of a surface of the second semiconductor substrate opposed to the first semiconductor substrate, a semiconductor region of a first conductivity type; and a pixel region of a second conductivity type located at a surface layer side of a surface of the second semiconductor substrate opposed to the first semiconductor substrate, a depth of the terrace surface from an opposing surface of the second semiconductor substrate to the first semiconductor substrate is deeper than a depth of the pixel region of the second photodiode array, the first side surface is closer to the first semiconductor substrate than the second side surface, and a crystal defect density in the first side surface is lower than a crystal defect density in the second side surface.