A wireless communication device that is configured to transmit a data packet including a packet number to another communication party, the wireless communication device comprising: a battery; a first storage unit to which power is supplied from the battery and in which the packet number is stored; a second storage unit in which a frequency that is used for communication with the other communication party is stored; an event detection unit to which the power is supplied from the battery and that detects an occurrence of an event; a control unit; a wireless communication unit that is configured to perform transmission and reception of the data packet between the wireless communication device and the other communication party, under the control of the control unit; and a connection control unit that is configured to supply power of the battery to the second storage unit, the control unit, and the wireless communication unit, and that is configured to cut off the supply of the power to the second storage unit, the control unit, and the wireless communication unit according to an instruction of the control unit, in a case where the battery is newly mounted, or in a case where the event detection unit detects the occurrence of the event, wherein, in a case where the event detection unit detects the occurrence of the event, the control unit is configured to generate a data packet including a wireless link establishment request, a message notifying the occurrence of the event, and the packet number that is stored in the first storage unit, to transmit the generated data packet from the wireless communication unit to the other communication party at the frequency that is stored in the second storage unit, to update the packet number that is stored in the first storage unit when a delivery acknowledgement is received from the other communication party, and to give an instruction to cut off the supply of the power to the connection control unit, characterized in that, in a case where the battery is newly mounted, the control unit is configured to attempt to establish synchronization between the wireless communication device and the other communication party, using the frequency that is stored in the second storage unit, wherein, in a case where the synchronization is not able to be established, the control unit is configured to attempt to establish synchronization while sequentially changing frequencies, and wherein, in the case where the synchronization is able to be established, the control unit is configured to rewrite the frequency that is stored in the second storage unit, as a value that results when the synchronization is established, to rewrite the packet number that is stored in the first storage unit, as an initial value that is determined in advance, and to give the instruction to cut off the supply of the power to the connection control unit. a battery; a first storage unit to which power is supplied from the battery and in which the packet number is stored; a second storage unit in which a frequency that is used for communication with the other communication party is stored; an event detection unit to which the power is supplied from the battery and that detects an occurrence of an event; a control unit; a wireless communication unit that is configured to perform transmission and reception of the data packet between the wireless communication device and the other communication party, under the control of the control unit; and a connection control unit that is configured to supply power of the battery to the second storage unit, the control unit, and the wireless communication unit, and that is configured to cut off the supply of the power to the second storage unit, the control unit, and the wireless communication unit according to an instruction of the control unit, in a case where the battery is newly mounted, or in a case where the event detection unit detects the occurrence of the event, wherein, in a case where the event detection unit detects the occurrence of the event, the control unit is configured to generate a data packet including a wireless link establishment request, a message notifying the occurrence of the event, and the packet number that is stored in the first storage unit, to transmit the generated data packet from the wireless communication unit to the other communication party at the frequency that is stored in the second storage unit, to update the packet number that is stored in the first storage unit when a delivery acknowledgement is received from the other communication party, and to give an instruction to cut off the supply of the power to the connection control unit, characterized in that, in a case where the battery is newly mounted, the control unit is configured to attempt to establish synchronization between the wireless communication device and the other communication party, using the frequency that is stored in the second storage unit, wherein, in a case where the synchronization is not able to be established, the control unit is configured to attempt to establish synchronization while sequentially changing frequencies, and wherein, in the case where the synchronization is able to be established, the control unit is configured to rewrite the frequency that is stored in the second storage unit, as a value that results when the synchronization is established, to rewrite the packet number that is stored in the first storage unit, as an initial value that is determined in advance, and to give the instruction to cut off the supply of the power to the connection control unit.