The present invention provides a pipeline A/D converter having resolution, allowable conversion processing rate and power consumption satisfying the requests of a system incorporating the pipeline A/D converter. The pipeline A/D converter in accordance with the present invention comprises a control section for outputting a control signal according to the operation state of an apparatus incorporating the pipeline A/D converter, and a pipeline A/D conversion section, the resolution and/or allowable conversion processing rate of which are switched by switching the capacitance in a built-in operational amplifier according to the control signal.