A clamp sensor comprising: a first clamp arm configured to pivot about a pivoting axis; a second clamp arm configured to pivot about the pivoting axis, the second clamp arm configured to clamp a measurement object in cooperation with the first clamp arm; a measurement unit provided on at least one of the first clamp arm and the second clamp arm, the measurement unit configured to measure a measured amount of the measurement object clamped by the first clamp arm and the second clamp arm; a first conductor provided on the first clamp arm so as to face an outer circumferential surface of the measurement object clamped by the first clamp arm and the second clamp arm, the first conductor including a first contact portion configured to come into contact with and separate from the second clamp arm; and a second conductor provided on the second clamp arm so as to face an outer circumferential surface of the measurement object clamped by the first clamp arm and the second clamp arm, the second conductor including a second contact portion configured to come into contact with and separate from the first contact portion, wherein one of the first contact portion and the second contact portion comprises a leaf spring portion protruding in a width direction parallel to the pivoting axis and inclined with respect to the width direction so as to approach other of the first contact portion and the second contact portion, and wherein the first contact portion and the second contact portion come into contact with each other in a state where one of the first contact portion and the second contact portion is pressed by the other and the leaf spring portion is bent by elastic deformation. a first clamp arm configured to pivot about a pivoting axis; a second clamp arm configured to pivot about the pivoting axis, the second clamp arm configured to clamp a measurement object in cooperation with the first clamp arm; a measurement unit provided on at least one of the first clamp arm and the second clamp arm, the measurement unit configured to measure a measured amount of the measurement object clamped by the first clamp arm and the second clamp arm; a first conductor provided on the first clamp arm so as to face an outer circumferential surface of the measurement object clamped by the first clamp arm and the second clamp arm, the first conductor including a first contact portion configured to come into contact with and separate from the second clamp arm; and a second conductor provided on the second clamp arm so as to face an outer circumferential surface of the measurement object clamped by the first clamp arm and the second clamp arm, the second conductor including a second contact portion configured to come into contact with and separate from the first contact portion, wherein one of the first contact portion and the second contact portion comprises a leaf spring portion protruding in a width direction parallel to the pivoting axis and inclined with respect to the width direction so as to approach other of the first contact portion and the second contact portion, and wherein the first contact portion and the second contact portion come into contact with each other in a state where one of the first contact portion and the second contact portion is pressed by the other and the leaf spring portion is bent by elastic deformation.