In an air compressor which can cope with an item to be replaced which is not a manufacturer's recommended item so as to enhance the safety, there is provided, as an example, an air compressor comprising a compressor body for compressing air, an item to be replaced (in detail, for example, a suction belt, a suction filter, a separator element and an oil filter) used during the operation of the compressor body, comprising a control device for computing a service time of the item to be replaced, from an operation time of the compressor body, discriminating whether the item to be replaced is a manufacturer's recommended item or not, determining whether or not the service time of the item to be replaced, which is discriminated as a manufacturer's recommended item, exceeds a preset first reference time, but determining whether the service time of the item to be replaced, which is discriminated as the one which is not the manufacturer's recommended item, exceeds a second reference time which has been preset so as to be shorter than the first reference time, and issuing an alarm if the reference time is exceeded.