A signal transmitting apparatus that may suppress generation of a noise voltage attributable to a common mode voltage is provided. A transistor P1 is connected between a first terminal of a sending coil and a power supply voltage. A transistor N1 is connected between the first terminal and a ground voltage. A transistor P2 is connected between a second terminal of the sending coil and the power supply voltage. A transistor N2 is connected between the second terminal and the ground voltage. In a period-PE1 a coil current flowing in a positive direction is generated by turning on the transistors P1 and N2 and turning off the transistors P2 and N1, and then the transistor N1 is turned on in response to turning off the transistor P1. In a period PE2, a coil current flowing in a negative direction is generated by turning off the transistors P1 and N2 and turning on the transistors P2 and N1, and then the transistor N2 is turned on in response to turning off the transistor P2.