An integration type A/D converter in which a dynamic range is enlarged while keeping a simple circuit configuration is provided. Offset potential of an integrator is to be variable. Specifically, offset potential in proportion to input potential is supplied to the integrator. Since an operation point of the integrator is changed in accordance with the input potential, a dynamic range can be enlarged. Further, reference potential input to the integrator in discharging is to be variable. Specifically, reference potential having a constant difference from the offset potential is input to the integrator. Accordingly, time necessary for discharging and the input potential are in proportion, so that a simple circuit configuration which is one feature of the integration type ADC can be maintained.