Abstract: A sensor device for sensor networks capable of saving power and securing accuracy and a method for transmitting data to a sensor network. The device includes: an oscillation-type sensor that oscillates with a mechanical vibrator; a data processor and communicator that processes a signal output from the oscillation-type sensor and transmits data to an external apparatus; a power supply that supplies electric power to the oscillation-type sensor and the data processor and communicator; and a power supply control unit that controls connection of a power supply line between the power supply and the oscillation-type sensor and connection of a power supply line between the power supply and the data processor and communicator. The power supply control unit connects the power supply line between the power supply and the oscillation-type sensor and then connects the power supply line between the power supply and the data processor and communicator.