A tire condition detecting apparatus includes a transmitting section, a receiving section, a control section, a property detecting section, and a battery, which is a power source for the apparatus. The control section operates in a control mode that is selected from a normal mode and a power saving mode. In the power saving mode, power consumption associated with reception of the wirelessly transmitted signal from the external device is less than that in the normal mode. When the amount of change in the electrical property of a valve stem detected by the property detecting section exceeds a reference change amount, the control section switches the control mode to the normal mode. The control section also switches the control mode to the power saving mode when a termination condition is met in the normal mode