A connection device for electronic equipment comprising: a case (110, 120) having an aperture into which a connection terminal can be inserted; and a connector comprising: an approximately rectangular tubular housing mounted within the case (110, 120) adjacent the aperture; a support provided in the form of a wall in the housing to substantially close the housing distal from the aperture; a contact terminal and a power terminal supported by the support; and an approximately rectangular tubular metallic shell mounted inside the housing; characterized in that the connection device further comprises: a seal provided along the outer circumference adjacent to the end of the connection terminal inserting side of the housing adjacent to and aligned with the aperture; wherein the seal is welded to the housing and made of a resin softer than the resin of the housing; and further comprising an additional seal provided in a recess behind the support in reference to the connection terminal inserting side and surrounded by a peripheral wall of the housing and the support; wherein the seal projects from the end of the connection terminal inserting side of the housing to the connection terminal inserting side and is brought into press contact with the surface of the connection terminal inserting side of the case (110, 120). a case (110, 120) having an aperture into which a connection terminal can be inserted; and a connector comprising: an approximately rectangular tubular housing mounted within the case (110, 120) adjacent the aperture; a support provided in the form of a wall in the housing to substantially close the housing distal from the aperture; a contact terminal and a power terminal supported by the support; and an approximately rectangular tubular metallic shell mounted inside the housing; an approximately rectangular tubular housing mounted within the case (110, 120) adjacent the aperture; a support provided in the form of a wall in the housing to substantially close the housing distal from the aperture; a contact terminal and a power terminal supported by the support; and an approximately rectangular tubular metallic shell mounted inside the housing; characterized in that the connection device further comprises: a seal provided along the outer circumference adjacent to the end of the connection terminal inserting side of the housing adjacent to and aligned with the aperture; wherein the seal is welded to the housing and made of a resin softer than the resin of the housing; and further comprising an additional seal provided in a recess behind the support in reference to the connection terminal inserting side and surrounded by a peripheral wall of the housing and the support; a seal provided along the outer circumference adjacent to the end of the connection terminal inserting side of the housing adjacent to and aligned with the aperture; wherein the seal is welded to the housing and made of a resin softer than the resin of the housing; and further comprising an additional seal provided in a recess behind the support in reference to the connection terminal inserting side and surrounded by a peripheral wall of the housing and the support; wherein the seal projects from the end of the connection terminal inserting side of the housing to the connection terminal inserting side and is brought into press contact with the surface of the connection terminal inserting side of the case (110, 120).