A wireless communication system, comprising: a portable device ( 20, 30); and a vehicle device configured to transmit information including a vehicle state, wherein the portable device ( 20, 30) and the vehicle device are configured so that bidirectional communication can be performed with each other, wherein the portable device ( 20, 30) includes an electronic key and a portable terminal, the electronic key includes a first near field communication unit that performs near field communication with the portable terminal and is configured to lock or unlock a vehicle door or start an engine through wireless communication with the vehicle device, the portable terminal includes a telecommunication unit that obtains, through an information network, information including procedures that should be taken in accordance with the vehicle state or state of the portable device ( 20, 30), a display, a control unit that shows on the display the vehicle state based on the information transmitted from the vehicle device or the state of the portable device ( 20, 30) based on information of the portable device, and a second near field communication unit that performs near field communication with the first near field communication unit, wherein the control unit obtains information including the vehicle state or information including the state of the electronic key through the near field communication performed with the electronic key, and wherein when a measure should be taken in accordance with the vehicle state or the state of the portable device ( 20, 30), the control unit shows on the display the procedures included in the information obtained by the telecommunication unit, characterized in that when near field communication with the portable terminal is established, the electronic key transmits information including a battery level of the electronic key to the portable terminal, when the control unit of the portable terminal receives the information including the battery level with the second near field communication unit, the control unit shows the battery level on the display, when the control unit of the portable terminal determines that the battery level is less than or equal to a threshold, the control unit shows on the display the procedures included in the information obtained by the telecommunication unit, and the procedures include at least one of procedures for replacing a battery of the electronic key, procedures for locking or unlocking a vehicle door when the battery of the electronic key is drained, and procedures for starting the engine when the battery of the electronic key is drained. a portable device ( 20, 30); and a vehicle device configured to transmit information including a vehicle state, wherein the portable device ( 20, 30) and the vehicle device are configured so that bidirectional communication can be performed with each other, wherein the portable device ( 20, 30) includes an electronic key and a portable terminal, the electronic key includes a first near field communication unit that performs near field communication with the portable terminal and is configured to lock or unlock a vehicle door or start an engine through wireless communication with the vehicle device, the portable terminal includes a telecommunication unit that obtains, through an information network, information including procedures that should be taken in accordance with the vehicle state or state of the portable device ( 20, 30), a display, a control unit that shows on the display the vehicle state based on the information transmitted from the vehicle device or the state of the portable device ( 20, 30) based on information of the portable device, and a second near field communication unit that performs near field communication with the first near field communication unit, wherein the control unit obtains information including the vehicle state or information including the state of the electronic key through the near field communication performed with the electronic key, and wherein when a measure should be taken in accordance with the vehicle state or the state of the portable device ( 20, 30), the control unit shows on the display the procedures included in the information obtained by the telecommunication unit, characterized in that when near field communication with the portable terminal is established, the electronic key transmits information including a battery level of the electronic key to the portable terminal, when the control unit of the portable terminal receives the information including the battery level with the second near field communication unit, the control unit shows the battery level on the display, when the control unit of the portable terminal determines that the battery level is less than or equal to a threshold, the control unit shows on the display the procedures included in the information obtained by the telecommunication unit, and the procedures include at least one of procedures for replacing a battery of the electronic key, procedures for locking or unlocking a vehicle door when the battery of the electronic key is drained, and procedures for starting the engine when the battery of the electronic key is drained.