Provided are a charged particle beam device and a detector capable of non-invasively observing a biochemical sample without a staining treatment or an immobilization treatment, with a simple and high observation throughput. An electron optics system, a stage 64, a sample chamber 100 holding a sample and including a first insulating layer 110 that is in contact with the sample, and a conductive layer 120 that is formed on the first insulating layer, signal detection circuits 20 and 50 connected to the conductive layer and detecting a current flowing through the conductive layer, and a main control unit 14 for controlling the electron optics system and the stage, wherein the main control unit 14 irradiates the conductive layer of the sample chamber placed on the stage with an electron beam from the electron optics system and is input with a detection signal from the signal detection circuit.