An automatic analyzer comprising: a rotatable cell disk holding a plurality of cells each able to contain a reaction mixture in which a sample and a reagent are mixed with each other on a circumference thereof and repeating rotation and termination; and a transmitted light measuring unit comprising a light source configured to irradiate a first of the plurality of cells with irradiation light from the light source during rotation of the cell disk and a transmitted light receiver configured to measure the light transmitted through the reaction mixture in the irradiated first cell; a scattered light measuring unit comprising a second light source configured to irradiate a second of the plurality of cells with irradiation light from the second light source during rotation of the cell disk and a second light receiver configured to measure the light scattered by the reaction mixture in the irradiated second cell; wherein the scattered light measuring unit includes a plurality of light receivers (33a - c) arranged in a plane perpendicular to a direction of movement of the irradiated second cell by the rotation of the cell disk and configured to receive the scattered light of each of different scattering angles, wherein the analyzer is configured to irradiate the second cell with irradiation light from the second light source and measure the light scattered by the reaction mixture in the cell during rotation of the cell disk and to accumulate in a data storage, while the cell disk is rotating, reaction measurement data of the transmitted light and scattered light of the reaction mixture in plural cells, characterized in that the light source of the transmitted light measuring unit is a halogen lamp and that the analyzer is configured such that integration time for the measurement of an irradiated cell is 2 msec or more by setting parameters to satisfy ψ ≤ ψ 0 = 17,7 ° and ψ 0 = arctan 2 * cw − 2 * v * t − 4 * mw − lcw − ldw / L wherein ψ is the angle between the optical axis of the irradiation light and the optical axis for receiving the scattered light when viewed from a direction perpendicular to a rotating plane of the cell disk, cw is the cell width, v is the cell speed, t is the integration time, mw is the width of the left and right margins from the cell wall surface, lew is the beam width of irradiation light irradiating the cell, Idw is the beam width of the scattered light and L is the cell optical path length. a rotatable cell disk holding a plurality of cells each able to contain a reaction mixture in which a sample and a reagent are mixed with each other on a circumference thereof and repeating rotation and termination; and a transmitted light measuring unit comprising a light source configured to irradiate a first of the plurality of cells with irradiation light from the light source during rotation of the cell disk and a transmitted light receiver configured to measure the light transmitted through the reaction mixture in the irradiated first cell; a scattered light measuring unit comprising a second light source configured to irradiate a second of the plurality of cells with irradiation light from the second light source during rotation of the cell disk and a second light receiver configured to measure the light scattered by the reaction mixture in the irradiated second cell; wherein the scattered light measuring unit includes a plurality of light receivers (33a - c) arranged in a plane perpendicular to a direction of movement of the irradiated second cell by the rotation of the cell disk and configured to receive the scattered light of each of different scattering angles, wherein the analyzer is configured to irradiate the second cell with irradiation light from the second light source and measure the light scattered by the reaction mixture in the cell during rotation of the cell disk and to accumulate in a data storage, while the cell disk is rotating, reaction measurement data of the transmitted light and scattered light of the reaction mixture in plural cells, characterized in that the light source of the transmitted light measuring unit is a halogen lamp and that the analyzer is configured such that integration time for the measurement of an irradiated cell is 2 msec or more by setting parameters to satisfy ψ ≤ ψ 0 = 17,7 ° and ψ 0 = arctan 2 * cw − 2 * v * t − 4 * mw − lcw − ldw / L wherein ψ is the angle between the optical axis of the irradiation light and the optical axis for receiving the scattered light when viewed from a direction perpendicular to a rotating plane of the cell disk, cw is the cell width, v is the cell speed, t is the integration time, mw is the width of the left and right margins from the cell wall surface, lew is the beam width of irradiation light irradiating the cell, Idw is the beam width of the scattered light and L is the cell optical path length.