A transmitter apparatus can detect and transmit tire information, such as tire air pressure information, even when a puncture in the tire is repaired by a repairing agent. The transmitter apparatus includes a sensor detecting the state of gas in a tire cavity region as tire information; a transmitter transmitting the detected tire information; and a wall covering the sensor and transmitter. The wall forms an internal space divided from the tire cavity region and includes a communicating hole providing communication between the internal space and tire cavity region. An inside opening part of the hole in a housing surface facing the internal space has a greater opening area than an outside opening part of the hole in the housing surface facing the tire cavity region. A wall surface facing the communicating hole includes a recessed part recessed toward the housing surface including the outside opening part.