An operation assistance system for a vehicle comprising an operation assistance device for vehicles and terminals capable of collecting voices of a plurality of persons who can be the occupants of the vehicle, even when the persons are not on board the vehicle, the operation assistance device comprising: a human relationship analysis unit; a human relationship storage unit; and an assistance information determination unit, wherein the operation assistance device is configured to obtain recommendation information suitable for an occupant composition including human relationships and provide the recommendation information for assisting a vehicle operation performed by an occupant, each terminal is configured to detect and transmit conversation voice data to the human relationship analysis unit; the human relationship analysis unit is configured to: acquire from the terminals conversation voice data of a plurality of persons who can be the occupants of the vehicle, to specify speakers; analyze the acquired conversation voice data for each of the specified speakers to extract a predetermined keyword; specify a speech pattern of each of the speakers on a basis of the keyword for each of the speakers, the speech pattern referring to how to use words and how to say things; specify conversation content on a basis of the conversation voice data of the plurality of persons; and analyze and quantify direct human relationships among the plurality of persons from the specified speech pattern and the specified conversation content, the human relationship storage unit is configured to preliminarily accumulate the direct human relationships among the plurality of persons who can be the occupants, the assistance information determination unit is configured to specify a plurality of occupants on board the vehicle and determine, on a basis of the direct human relationships accumulated in the human relationship storage unit, assistance information for the vehicle operation determined to be recommended in accordance with the human relationships among the plurality of occupants. a human relationship analysis unit; a human relationship storage unit; and an assistance information determination unit, wherein the operation assistance device is configured to obtain recommendation information suitable for an occupant composition including human relationships and provide the recommendation information for assisting a vehicle operation performed by an occupant, each terminal is configured to detect and transmit conversation voice data to the human relationship analysis unit; the human relationship analysis unit is configured to: acquire from the terminals conversation voice data of a plurality of persons who can be the occupants of the vehicle, to specify speakers; analyze the acquired conversation voice data for each of the specified speakers to extract a predetermined keyword; specify a speech pattern of each of the speakers on a basis of the keyword for each of the speakers, the speech pattern referring to how to use words and how to say things; specify conversation content on a basis of the conversation voice data of the plurality of persons; and analyze and quantify direct human relationships among the plurality of persons from the specified speech pattern and the specified conversation content, acquire from the terminals conversation voice data of a plurality of persons who can be the occupants of the vehicle, to specify speakers; analyze the acquired conversation voice data for each of the specified speakers to extract a predetermined keyword; specify a speech pattern of each of the speakers on a basis of the keyword for each of the speakers, the speech pattern referring to how to use words and how to say things; specify conversation content on a basis of the conversation voice data of the plurality of persons; and analyze and quantify direct human relationships among the plurality of persons from the specified speech pattern and the specified conversation content, the human relationship storage unit is configured to preliminarily accumulate the direct human relationships among the plurality of persons who can be the occupants, the assistance information determination unit is configured to specify a plurality of occupants on board the vehicle and determine, on a basis of the direct human relationships accumulated in the human relationship storage unit, assistance information for the vehicle operation determined to be recommended in accordance with the human relationships among the plurality of occupants.