A transmitter that is provided in each wheel assembly of a vehicle and is configured to transmit transmission data to a receiver mounted in the vehicle, the vehicle having a rotation angle detecting section (21 to 24) that detects a rotation angle of each of the wheel assemblies as a detection value, the transmitter comprising: a transmission storage section, which stores identification information; a transmission section, which is configured to transmit the transmission data including verification data, which is used by the receiver to verify the identification information stored in the transmission storage section against identification information of each transmitter registered in the receiver; and a control section, which is configured to perform specific angle transmission, in which the control section causes the transmission section to transmit the transmission data when detecting that the rotation angle of the corresponding wheel assembly is any one of a plurality of predetermined specific angles, so as to cause the receiver to identify the wheel assembly to which the corresponding transmitter is attached, characterized in that the control section is configured to change, at the performance of transmission at the specific angle and in accordance with the specific angle, data that is included in the transmission data and does not indicate the rotation angle of the wheel assembly so as to cause the receiver to recognize the transmission data transmitted at the same specific angle based on a manner in which the data not indicating the rotation angle of the wheel assembly is changed in accordance with the specific angle, and to collect, for each piece of the transmission data transmitted at the same specific angle, the detection values, which are detected by the rotation angle detecting section (21 to 24), upon reception of the transmission data. a transmission storage section, which stores identification information; a transmission section, which is configured to transmit the transmission data including verification data, which is used by the receiver to verify the identification information stored in the transmission storage section against identification information of each transmitter registered in the receiver; and a control section, which is configured to perform specific angle transmission, in which the control section causes the transmission section to transmit the transmission data when detecting that the rotation angle of the corresponding wheel assembly is any one of a plurality of predetermined specific angles, so as to cause the receiver to identify the wheel assembly to which the corresponding transmitter is attached, characterized in that the control section is configured to change, at the performance of transmission at the specific angle and in accordance with the specific angle, data that is included in the transmission data and does not indicate the rotation angle of the wheel assembly so as to cause the receiver to recognize the transmission data transmitted at the same specific angle based on a manner in which the data not indicating the rotation angle of the wheel assembly is changed in accordance with the specific angle, and to collect, for each piece of the transmission data transmitted at the same specific angle, the detection values, which are detected by the rotation angle detecting section (21 to 24), upon reception of the transmission data.