An automatic analyzer for analyzing samples, comprising: an analysis unit including an electrolyte measurement unit for measuring an electrolyte concentration in the samples using an ion selection electrode and a biochemical measurement unit for measuring biochemical components in the samples by measuring an absorbance of a reaction solution; a transport unit for transporting the samples to the analysis unit, the transport unit comprising a transport control unit for controlling transport operations for transporting the samples to the analysis unit; and a control unit for controlling the analysis unit and the transport unit; wherein the electrolyte measurement unit is adapted to measure an electromotive force of an internal standard solution as a pre-measurement operation required before each electrolyte concentration measurement and wherein no such pre-measurement operation is required before the biochemical component measurement in the biochemical measurement unit; and wherein the control unit is adapted to receive in advance from the transport control unit a time required for transporting a sample by the transport unit to the analysis unit and to determine an optimal timing at which the sample is started to be transported from the transport unit to the analysis unit based on a scheduled dispensing operation time planned in advance and the time required for transporting the sample by the transport unit to the analysis unit so as to control the transport unit to transport the sample to the analysis unit in time for starting an aspirating operation on the sample before the scheduled dispensing operation time in the electrolyte measurement unit or the biochemical measurement unit, while allowing the electrolyte measurement in the analysis unit to perform the required pre-measurement operations; and wherein the optimal timing is a timing at which the scheduled dispensing operation time minus the time required for transporting the sample from the transport unit to the analysis unit is reached. an analysis unit including an electrolyte measurement unit for measuring an electrolyte concentration in the samples using an ion selection electrode and a biochemical measurement unit for measuring biochemical components in the samples by measuring an absorbance of a reaction solution; a transport unit for transporting the samples to the analysis unit, the transport unit comprising a transport control unit for controlling transport operations for transporting the samples to the analysis unit; and a control unit for controlling the analysis unit and the transport unit; wherein the electrolyte measurement unit is adapted to measure an electromotive force of an internal standard solution as a pre-measurement operation required before each electrolyte concentration measurement and wherein no such pre-measurement operation is required before the biochemical component measurement in the biochemical measurement unit; and wherein the control unit is adapted to receive in advance from the transport control unit a time required for transporting a sample by the transport unit to the analysis unit and to determine an optimal timing at which the sample is started to be transported from the transport unit to the analysis unit based on a scheduled dispensing operation time planned in advance and the time required for transporting the sample by the transport unit to the analysis unit so as to control the transport unit to transport the sample to the analysis unit in time for starting an aspirating operation on the sample before the scheduled dispensing operation time in the electrolyte measurement unit or the biochemical measurement unit, while allowing the electrolyte measurement in the analysis unit to perform the required pre-measurement operations; and wherein the optimal timing is a timing at which the scheduled dispensing operation time minus the time required for transporting the sample from the transport unit to the analysis unit is reached.