A connection terminal comprising: an electrical connection portion into which a mating connection portion, which is formed in a tab shape, of a mating terminal can be inserted, the electrical connection portion being formed in a tubular shape; an elastic piece provided in the electrical connection portion, being elastically deformable, and including a first contact portion configured to be brought in contact with the mating connection portion; an opposing wall provided in the electrical connection portion and disposed opposite to the first contact portion of the elastic piece; a pair of second contact portions (13, 15) provided on the opposing wall and disposed on a front side and a rear side in an insertion direction of the mating connection portion, and projecting toward an elastic piece side and configured to be in contact with the mating connection portion; and a curved surface provided on the opposing wall and located between the pair of second contact portions (13, 15) along the insertion direction of the mating connection portion, wherein the curved surface includes: a first curved surface located on the rear side in the insertion direction of the mating connection portion; and a second curved surface located on the front side in the insertion direction of the mating connection portion, on which the mating connection portion is configured to slide when the mating connection portion is inserted into the electrical connection portion while being tilted; characterized in that a curvature of the second curved surface is set larger than a curvature of the first curved surface, and the first curved surface is provided from the second contact portion on the rear side in the insertion direction of the mating connection portion to a portion located on the front side in the insertion direction of the mating connection portion with respect to a portion facing the first contact portion. an electrical connection portion into which a mating connection portion, which is formed in a tab shape, of a mating terminal can be inserted, the electrical connection portion being formed in a tubular shape; an elastic piece provided in the electrical connection portion, being elastically deformable, and including a first contact portion configured to be brought in contact with the mating connection portion; an opposing wall provided in the electrical connection portion and disposed opposite to the first contact portion of the elastic piece; a pair of second contact portions (13, 15) provided on the opposing wall and disposed on a front side and a rear side in an insertion direction of the mating connection portion, and projecting toward an elastic piece side and configured to be in contact with the mating connection portion; and a curved surface provided on the opposing wall and located between the pair of second contact portions (13, 15) along the insertion direction of the mating connection portion, wherein the curved surface includes: a first curved surface located on the rear side in the insertion direction of the mating connection portion; and a second curved surface located on the front side in the insertion direction of the mating connection portion, on which the mating connection portion is configured to slide when the mating connection portion is inserted into the electrical connection portion while being tilted; characterized in that a curvature of the second curved surface is set larger than a curvature of the first curved surface, and the first curved surface is provided from the second contact portion on the rear side in the insertion direction of the mating connection portion to a portion located on the front side in the insertion direction of the mating connection portion with respect to a portion facing the first contact portion. a first curved surface located on the rear side in the insertion direction of the mating connection portion; and a second curved surface located on the front side in the insertion direction of the mating connection portion, on which the mating connection portion is configured to slide when the mating connection portion is inserted into the electrical connection portion while being tilted; characterized in that a curvature of the second curved surface is set larger than a curvature of the first curved surface, and the first curved surface is provided from the second contact portion on the rear side in the insertion direction of the mating connection portion to a portion located on the front side in the insertion direction of the mating connection portion with respect to a portion facing the first contact portion.