The present technology relates to a transmitter, a transmission method, a receiver, and a reception method, and particularly to a transmitter, a transmission method, a receiver, and a reception method that can keep upsizing and cost increase to a minimum. The transmitter and the receiver have a detection mode and a communication mode as operation modes. The detection mode detects contact between a first waveguide on the side of the transmitter and a second waveguide on the side of the receiver. The communication mode sends or receives a modulated signal, acquired through frequency conversion of a baseband signal, via the first and second waveguides. The transmitter sends a given signal to the first waveguide in the detection mode. The transmitter and the receiver go from the detection mode to the communication mode in response to a given signal received by the receiver via the second waveguide and send and receive the modulated signal via the first and second waveguides in the communication mode. The present technology is applicable, for example, to communication via waveguides.