A corrosive environment sensor for measuring corrosive environment inside a space between a first member that is a conductor and a second member that is a conductor or insulator includes: a base having a surface which cam face the first member that is a conductor; and an electrode which is provided on the surface of the base and formed with a material different in ionization tendency from the first member and which faces at a distance the first member so as to form a galvanic coupling with the first member, and the corrosive environment sensor measures a galvanic current between the electrode and the first member.