Provided are an endoscope, a processor, and an adjustment device capable of preventing an amplification factor by a GCA unit from varying, regardless of the type of light source. An endoscope 2 is provided with: an imaging unit 22 that receives light from the outside and generates an image signal according to the amount of light received； a GCA unit 52 that amplifies the image signal generated by the imaging unit 22 at a prescribed amplification factor； a light source amplification factor recording unit 551 that records light source amplification factor information obtained by associating each of a plurality of types of light sources with the amplification factor of the image signal by the GCA unit； an acquisition unit 561 that acquires light source information indicating the type of light source provided to a light source device that irradiates a subject with an illumination light； and an amplification control unit 562 control unit that refers to the light source amplification factor information recorded by the light source amplification factor recording unit 551 to cause the GCA unit 52 to amplify the image signal at an amplification factor according to the light source information acquired by the acquisition unit 561.
