A biosensor device which is possible to be downsized and potable, is free of the problem of solution outflow, and enables detection accurately and stably is realized. A biosensor device (30) having an artificial lipid membrane is provided with an artificial lipid membrane (1) having first and second membrane surfaces (1a, 1b) which are located opposite each other, a first chamber (11a) for encapsulating a first electrolyte solution (2a) in contact with the first membrane surface (1a) of the artificial lipid membrane, a second chamber (11b) for encapsulating a second electrolyte solution (2b) in contact with the second membrane surface (1b) of the artificial lipid membrane, first electrodes (3a, 3a′) for contacting the first electrolyte solution (2a) in the first chamber (11a), and second electrodes (3b, 3b′) for contacting the second electrolyte solution (2b) in the second chamber (11b), wherein the second chamber (11b) has gas permeability at its wall portion (10) for encapsulating the second electrolyte solution (2b) in at least a wall thickness direction.