A load driving device including a converter, an output circuit and a timer circuit is provided. The converter receives a communication frame including a data signal through a serial communication and performs parallel conversion on the data signal to output an instruction signal instructing the output circuit to transition to a first state when the data signal includes first serial data and output an instruction signal instructing the output circuit to transition to a second state when the data signal includes second serial data. A timer circuit measures a duration time during which the converter receives the first serial data. When the measuring duration time arrives at an abnormality determination time, the timer circuit forces the output circuit to transition to the second state when the measuring duration time arrives at an abnormality determination time.