A power management device for vehicles employed in a vehicle including a vehicle-mounted power storage device (16, 26) that selectively supplies and receives electric power with respect to an external power source device, the power management device comprising: a communication control section that performs interactive communication to selectively supply and receive the electric power with respect to the external power source device; and a supplying/receiving control section that controls supplying/receiving of the electric power, the power management device being characterized by a schedule generating section for generating a schedule for selectively supplying and receiving the electric power based on information obtained by the communication control section through the interactive communication, wherein the supplying/receiving control section is switchable between a great power state and a decreased state in which a power consumption amount is smaller than in the great power state, if a condition that the supplying/receiving control section is in the great power state is satisfied, control of the supplying/receiving of the electric power is allowed, the supplying/receiving control section is switched to the decreased state if a condition that a standby time until the supplying/receiving of the electric power is started according to the schedule generated by the schedule generating section is not less than a predetermined time is satisfied, wherein the standby time is a time difference between the charging starting time and a current time point, if the supplying/receiving control section is in the decreased state before the vehicle-mounted power storage device ( 16, 26) and the external power source device selectively supply and receive the electric power with respect to each other, the communication control section performs the interactive communication, when the supplying/receiving control section is in the decreased state, in the standby period until the supplying/receiving of the electric power is started, if it is determined that the electric power information including the time zones and the electric power charges or the upper limit of the charging electric power has been changed based on the information obtained through communication with the external power source device, the communication control section changes the schedule by means of the schedule generating section. a communication control section that performs interactive communication to selectively supply and receive the electric power with respect to the external power source device; and a supplying/receiving control section that controls supplying/receiving of the electric power, the power management device being characterized by a schedule generating section for generating a schedule for selectively supplying and receiving the electric power based on information obtained by the communication control section through the interactive communication, wherein the supplying/receiving control section is switchable between a great power state and a decreased state in which a power consumption amount is smaller than in the great power state, if a condition that the supplying/receiving control section is in the great power state is satisfied, control of the supplying/receiving of the electric power is allowed, the supplying/receiving control section is switched to the decreased state if a condition that a standby time until the supplying/receiving of the electric power is started according to the schedule generated by the schedule generating section is not less than a predetermined time is satisfied, wherein the standby time is a time difference between the charging starting time and a current time point, if the supplying/receiving control section is in the decreased state before the vehicle-mounted power storage device ( 16, 26) and the external power source device selectively supply and receive the electric power with respect to each other, the communication control section performs the interactive communication, when the supplying/receiving control section is in the decreased state, in the standby period until the supplying/receiving of the electric power is started, if it is determined that the electric power information including the time zones and the electric power charges or the upper limit of the charging electric power has been changed based on the information obtained through communication with the external power source device, the communication control section changes the schedule by means of the schedule generating section.