A wireless transmitter is arranged outside of a living body and configured to be able to perform wireless transmission utilizing magnetic coupling for an in-vivo observation apparatus inside of the living body, the wireless transmitter including: a magnetic field generation section including a plurality of plane coils inside, the plurality of plane coils being arranged such that each of coil surfaces is positioned on a same plane or arranged in a layer such that the coil surfaces are parallel to each other； a power source section configured to supply currents to be applied to the plurality of plane coils； a phase switch section configured to perform operation for supplying the currents supplied from the power source section to the plurality of plane coils while switching phases of the currents； and a control section configured to control the power source section and the phase switch section to sequentially and repeatedly switch states of the currents flowing through the plurality of plane coils at each predetermined period.
