An electrical connector comprising; an end portion of a flat circuit device which forms a connectively engaging protrusion on which a plurality of contacting terminals are arranged and a supporting board portion for supporting the connectively engaging protrusion, and first and second conductive shells (13, 14; 71, 72) having respectively first and second plate portions (30, 40; 75, 85) opposite to each other with the supporting board portion between the first and second plate portions (30, 40; 75, 85), characterized in that the flat circuit device contains a board-shaped insulating base which has a portion thereof constituting the supporting board portion and another portion thereof extending from the supporting board portion to constitute the connectively engaging protrusion and in which a plurality of strip-shaped conductors are buried to be arranged in parallel with each other and to form with end portions thereof respectively the contacting terminals arranged on the connectively engaging protrusion to expose to the outside of the board-shaped insulating base for coming into contact directly and respectively with conductive contacts of a mating electrical connector, and in that the first conductive shell (13; 71) is attached to the supporting board portion with a pair of engaging portions (33, 36; 78; 81) thereof engaging respectively with engaging edged recesses (20A, 20B) provided on the flat circuit device to be contiguous to the supporting board portion and the first plate portion (30; 75) thereof covering directly a first surface of the supporting board portion and the second conductive shell (14; 72) is positioned to the supporting board portion with a pair of engaging portions (42, 44; 87; 89) thereof engaging respectively with the engaging portions (33, 36; 78; 81) of the first conductive shell (13; 71) attached to the supporting board portion and the second plate portion (40; 85) thereof covering directly a second surface opposite to the first surface of the supporting board portion, so that the first and second conductive shells (13, 14) are operative to hold the connectively engaging protrusion supported by the supporting board portion at the end portion of the flat circuit device for causing the same to engage with a mating electrical connector in such a manner that the contacting terminals are exposed on the connectively engaging protrusion. an end portion of a flat circuit device which forms a connectively engaging protrusion on which a plurality of contacting terminals are arranged and a supporting board portion for supporting the connectively engaging protrusion, and first and second conductive shells (13, 14; 71, 72) having respectively first and second plate portions (30, 40; 75, 85) opposite to each other with the supporting board portion between the first and second plate portions (30, 40; 75, 85), characterized in that the flat circuit device contains a board-shaped insulating base which has a portion thereof constituting the supporting board portion and another portion thereof extending from the supporting board portion to constitute the connectively engaging protrusion and in which a plurality of strip-shaped conductors are buried to be arranged in parallel with each other and to form with end portions thereof respectively the contacting terminals arranged on the connectively engaging protrusion to expose to the outside of the board-shaped insulating base for coming into contact directly and respectively with conductive contacts of a mating electrical connector, and in that the first conductive shell (13; 71) is attached to the supporting board portion with a pair of engaging portions (33, 36; 78; 81) thereof engaging respectively with engaging edged recesses (20A, 20B) provided on the flat circuit device to be contiguous to the supporting board portion and the first plate portion (30; 75) thereof covering directly a first surface of the supporting board portion and the second conductive shell (14; 72) is positioned to the supporting board portion with a pair of engaging portions (42, 44; 87; 89) thereof engaging respectively with the engaging portions (33, 36; 78; 81) of the first conductive shell (13; 71) attached to the supporting board portion and the second plate portion (40; 85) thereof covering directly a second surface opposite to the first surface of the supporting board portion, so that the first and second conductive shells (13, 14) are operative to hold the connectively engaging protrusion supported by the supporting board portion at the end portion of the flat circuit device for causing the same to engage with a mating electrical connector in such a manner that the contacting terminals are exposed on the connectively engaging protrusion.