A communication system for a vehicle that has a plurality of communication lines (12A/B, 13A/B, 21-1) each formed in a loop form and in which a transmission path having a joint connector (14A/B/C, 15A/B/C) provided at each of a plurality of connection positions on the communication line (12A/B, 13A/B, 21-1) is formed in each of a plurality of zones (Z1, Z2), the communication system comprising: two or more disconnection detection parts (27, 28) that detect presence or absence of disconnection in one or more paths included in the communication line (12A/B, 13A/B); and a communication path control part (27, 28, 41, 42); said communication system being characterized in that further comprises: a plurality of zone management parts (41, 42) each of which manages a communication path of one of the plurality of zones (Z1, Z2);a central management part that manages all communication paths in the plurality of zones (Z1, Z2) in cooperation with the plurality of zone management parts (41, 42); one or more path switches (22-1, 22-2) that are provided for each of the plurality of zones (Z1, Z2); and in that the two or more disconnection detection parts (27, 28) are provided for each of the plurality of zones (Z1, Z2); the path switch (22-1, 22-2) that is controllable to cut off a part of the communication line (12A/B, 13A/B, 21-1) in a steady state is provided inside or near the plurality of the joint connectors (14A/B/C, 15A/B/C); the disconnection detection part (27, 28) detects presence or absence of disconnection in one or more paths included in the communication line (12A/B, 13A/B) for each of the plurality of zones (Z1, Z2) and is provided inside or near the plurality of the joint connectors (14A/B/C, 15A/B/C); each of the plurality of zone management parts (41, 42) and the central management part holds a routing map for controlling the communication path; and when the disconnection detection part (27, 28) detects presence of disconnection, the communication path control part (27, 28, 41, 42) switches one or a plurality of the path switches (22-1, 22-2) to a connected state, and changes content of the routing map to enable use of a path passing through the path switch (22-1, 22-2). two or more disconnection detection parts (27, 28) that detect presence or absence of disconnection in one or more paths included in the communication line (12A/B, 13A/B); and a communication path control part (27, 28, 41, 42); said communication system being characterized in that further comprises: a plurality of zone management parts (41, 42) each of which manages a communication path of one of the plurality of zones (Z1, Z2);a central management part that manages all communication paths in the plurality of zones (Z1, Z2) in cooperation with the plurality of zone management parts (41, 42); one or more path switches (22-1, 22-2) that are provided for each of the plurality of zones (Z1, Z2); and in that the two or more disconnection detection parts (27, 28) are provided for each of the plurality of zones (Z1, Z2); the path switch (22-1, 22-2) that is controllable to cut off a part of the communication line (12A/B, 13A/B, 21-1) in a steady state is provided inside or near the plurality of the joint connectors (14A/B/C, 15A/B/C); the disconnection detection part (27, 28) detects presence or absence of disconnection in one or more paths included in the communication line (12A/B, 13A/B) for each of the plurality of zones (Z1, Z2) and is provided inside or near the plurality of the joint connectors (14A/B/C, 15A/B/C); each of the plurality of zone management parts (41, 42) and the central management part holds a routing map for controlling the communication path; and when the disconnection detection part (27, 28) detects presence of disconnection, the communication path control part (27, 28, 41, 42) switches one or a plurality of the path switches (22-1, 22-2) to a connected state, and changes content of the routing map to enable use of a path passing through the path switch (22-1, 22-2). a plurality of zone management parts (41, 42) each of which manages a communication path of one of the plurality of zones (Z1, Z2);a central management part that manages all communication paths in the plurality of zones (Z1, Z2) in cooperation with the plurality of zone management parts (41, 42); one or more path switches (22-1, 22-2) that are provided for each of the plurality of zones (Z1, Z2); and in that the two or more disconnection detection parts (27, 28) are provided for each of the plurality of zones (Z1, Z2); the path switch (22-1, 22-2) that is controllable to cut off a part of the communication line (12A/B, 13A/B, 21-1) in a steady state is provided inside or near the plurality of the joint connectors (14A/B/C, 15A/B/C); the disconnection detection part (27, 28) detects presence or absence of disconnection in one or more paths included in the communication line (12A/B, 13A/B) for each of the plurality of zones (Z1, Z2) and is provided inside or near the plurality of the joint connectors (14A/B/C, 15A/B/C); each of the plurality of zone management parts (41, 42) and the central management part holds a routing map for controlling the communication path; and when the disconnection detection part (27, 28) detects presence of disconnection, the communication path control part (27, 28, 41, 42) switches one or a plurality of the path switches (22-1, 22-2) to a connected state, and changes content of the routing map to enable use of a path passing through the path switch (22-1, 22-2).