The free ends of the upper touching portions 312 of the two upper ground terminals 31 abut against an inner surface of a top wall of the first receiving chamber 411. Free ends of the lower touching portions 322 of the two lower ground terminals 32 abut against an inner surface of a bottom wall of the first receiving chamber 411. A front surface of the base portion 13 abuts against the rear surface of the base body 41. The upper dielectric body 15 with the upper row of the conductive terminals 20 and the two upper ground terminals 31 being integrally molded thereto, and the lower dielectric body 16 with the lower row of the conductive terminals 20 and the two lower ground terminals 32 being molded thereto are assembled together. The upper base portion 151 and the lower base portion 161 are assembled into the base portion 13. The upper connecting portion 152 and the lower connecting portion 162 are assembled into the connecting portion 14.