An operating method of a terminal for a multinet aggregation service, comprising: receiving access information of a gateway providing the multinet aggregation service from an authentication server; accessing the gateway corresponding to the access information through a first network to perform a connection procedure, when a packet transmitted to a server (400, 500) is generated; generating a first subflow through the first network when the connection procedure to the gateway succeeds; and generating a second subflow joined to the first subflow through a second network, wherein the access information helps the terminal to access the gateway, wherein the performing of the connection procedure includes: transmitting user information to the gateway; receiving a user authentication result determined based on the user information from the gateway; transmitting server information to the gateway when the user authentication result succeeds; and receiving the connection result to the server (400, 500) from the gateway, wherein the gateway is a network apparatus that is positioned at a contact between the first network and the second network and is proxy-connected to the terminal and the server (400, 500) for data communication between the terminal and the server (400, 500) through the first subflow and the second subflow when the connection procedure to the gateway succeeds, said method further comprising accessing the server (400, 500) through a default route when the connection procedure to the gateway fails. receiving access information of a gateway providing the multinet aggregation service from an authentication server; accessing the gateway corresponding to the access information through a first network to perform a connection procedure, when a packet transmitted to a server (400, 500) is generated; generating a first subflow through the first network when the connection procedure to the gateway succeeds; and generating a second subflow joined to the first subflow through a second network, wherein the access information helps the terminal to access the gateway, wherein the performing of the connection procedure includes: transmitting user information to the gateway; receiving a user authentication result determined based on the user information from the gateway; transmitting server information to the gateway when the user authentication result succeeds; and receiving the connection result to the server (400, 500) from the gateway, transmitting user information to the gateway; receiving a user authentication result determined based on the user information from the gateway; transmitting server information to the gateway when the user authentication result succeeds; and receiving the connection result to the server (400, 500) from the gateway, wherein the gateway is a network apparatus that is positioned at a contact between the first network and the second network and is proxy-connected to the terminal and the server (400, 500) for data communication between the terminal and the server (400, 500) through the first subflow and the second subflow when the connection procedure to the gateway succeeds, said method further comprising accessing the server (400, 500) through a default route when the connection procedure to the gateway fails.