A shield shell system, comprising: a first caulking ring; a plurality of second caulking rings; and a shield shell to be connected to a case made of metal, a side to be fitted to the case being referred to as a front side concerning a front-back direction, the shield shell comprising: a shell main body including a case connecting portion to be connected to the case; a single collective shield connecting portion provided on the shell main body and formed into a tubular shape; a plurality of individual-core shield connecting portions provided on the shell main body and formed into a tubular shape; a first shielding member is configured to be selectively mounted on an outer periphery of the collective shield connecting portion; a plurality of second shielding members are configured to be selectively mounted on the outer peripheries of the individual-core shield connecting portions; wherein the collective shield connecting portion is formed to project backward from a front wall portion continuous with the case connecting portion on the shell main body, and the plurality of individual-core shield connecting portions is capable of being caulked together with the plurality of second shielding members by the plurality of second caulking rings, the collective shield connecting portion is configured to be caulked together with the first shielding member by the first caulking ring, and the plurality of individual-core shield connecting portions are provided on a rear wall portion of the collective shield connecting portion, which is arranged at a side of the shell main body opposite to the front wall portion and in which a locking hole to be locked with a locking projection of a housing is provided. a first caulking ring; a plurality of second caulking rings; and a shield shell to be connected to a case made of metal, a side to be fitted to the case being referred to as a front side concerning a front-back direction, the shield shell comprising: a shell main body including a case connecting portion to be connected to the case; a single collective shield connecting portion provided on the shell main body and formed into a tubular shape; a plurality of individual-core shield connecting portions provided on the shell main body and formed into a tubular shape; a first shielding member is configured to be selectively mounted on an outer periphery of the collective shield connecting portion; a plurality of second shielding members are configured to be selectively mounted on the outer peripheries of the individual-core shield connecting portions; wherein the collective shield connecting portion is formed to project backward from a front wall portion continuous with the case connecting portion on the shell main body, and the plurality of individual-core shield connecting portions is capable of being caulked together with the plurality of second shielding members by the plurality of second caulking rings, a shell main body including a case connecting portion to be connected to the case; a single collective shield connecting portion provided on the shell main body and formed into a tubular shape; a plurality of individual-core shield connecting portions provided on the shell main body and formed into a tubular shape; a first shielding member is configured to be selectively mounted on an outer periphery of the collective shield connecting portion; a plurality of second shielding members are configured to be selectively mounted on the outer peripheries of the individual-core shield connecting portions; wherein the collective shield connecting portion is formed to project backward from a front wall portion continuous with the case connecting portion on the shell main body, and the plurality of individual-core shield connecting portions is capable of being caulked together with the plurality of second shielding members by the plurality of second caulking rings, the collective shield connecting portion is configured to be caulked together with the first shielding member by the first caulking ring, and the plurality of individual-core shield connecting portions are provided on a rear wall portion of the collective shield connecting portion, which is arranged at a side of the shell main body opposite to the front wall portion and in which a locking hole to be locked with a locking projection of a housing is provided.