A living body observation system of the invention includes a living body information acquiring apparatus including: a living body information acquiring section; a wireless transmission section; a power source section for supplying driving power for driving the living body information acquiring section and the wireless transmission section; a magnetic field detecting section for outputting a detection result of a magnetic field from outside as an electric signal; and a power supply control section for controlling a supplying state of the driving power based on the electric signal, a magnetic field generating coil, a driving circuit for outputting a drive signal to the magnetic field generating coil, a switch for switching a generation state of a magnetic field, and a timer for outputting a signal for stopping output of the drive signal when a predetermined period has passed following switching from off to on of the switch.