The invention provides a novel board-to-board coaxial connector in which the allowable range for dispersions of the relative distance of two boards, and of the relative position along the board faces is large, the relative distance and position are tolerated so that instantaneous disconnection due to vibrations, an impact of dropping, or the like does not occur, and the contact reliability of a center conductor and a counter contact portion is excellent. The coaxial connector of the invention consists of a receptacle 4 which is to be surface mounted to one board 2, and a plug 5 which is to be surface mounted to another board 3. A contact portion 17 is formed in an internal conductor housing portion 12 of a plug body 9 into which a receptacle center conductor 7 is to be inserted. The contact portion has: a stationary contact piece portion 10b which is perpendicularly bent from a solder connecting portion 10a of a plug internal conductor 10 to extend in the axial direction of the connector; and movable contact piece portions 10c which are continuous to the stationary contact piece portion, which are juxtaposed in a circumferential direction of the connector, and which extend in the axial direction of the connector. When the center conductor 7 is inserted into the internal conductor housing portion 12, the movable contact piece portions 10c are elastically displaced in a direction perpendicular to the axial direction of the connector to be elastically contacted with the outer circumferential face of the center conductor 7, together with the stationary contact piece portion 10b.