A preprocessing device comprising: a setting receiving section for receiving, for each sample, setting of a plurality of types of preprocessing and a parameter for each preprocessing; a plurality of preprocessing sections, each being provided for performing one of the plurality of types of preprocessing; a transport arm for sequentially transporting, between the plurality of preprocessing sections, a plurality of containers including a separation container with a separating layer through which a specific component in a sample is separated and a collection container for collecting a sample extracted by the separating layer; a preprocessing execution section configured to control the plurality of preprocessing sections and the transport arm based on the parameter received by the setting receiving section, so that the plurality of types of preprocessing set for each of different samples are performed simultaneously in parallel, and independently, for each of the different samples, such that even while preprocessing is performed for one sample of the different samples at one of the plurality of preprocessing sections, the separation container or collection container containing another sample of the different samples can be transported by the transport arm to another one of the plurality of preprocessing sections, and preprocessing of the another sample can be independently performed, such that if preprocessing of one sample takes a long time, preprocessing of other samples can proceed, and characterized in that the preprocessing execution section manages a vacancy status and the processing status of each preprocessing section and is adapted to perform control in such a way that preprocessing is not performed on different samples at a same preprocessing section at a same time. a setting receiving section for receiving, for each sample, setting of a plurality of types of preprocessing and a parameter for each preprocessing; a plurality of preprocessing sections, each being provided for performing one of the plurality of types of preprocessing; a transport arm for sequentially transporting, between the plurality of preprocessing sections, a plurality of containers including a separation container with a separating layer through which a specific component in a sample is separated and a collection container for collecting a sample extracted by the separating layer; a preprocessing execution section configured to control the plurality of preprocessing sections and the transport arm based on the parameter received by the setting receiving section, so that the plurality of types of preprocessing set for each of different samples are performed simultaneously in parallel, and independently, for each of the different samples, such that even while preprocessing is performed for one sample of the different samples at one of the plurality of preprocessing sections, the separation container or collection container containing another sample of the different samples can be transported by the transport arm to another one of the plurality of preprocessing sections, and preprocessing of the another sample can be independently performed, such that if preprocessing of one sample takes a long time, preprocessing of other samples can proceed, and characterized in that the preprocessing execution section manages a vacancy status and the processing status of each preprocessing section and is adapted to perform control in such a way that preprocessing is not performed on different samples at a same preprocessing section at a same time.