A light scattering measuring apparatus, comprising: light sources configured to generate incident light to irradiate a sample; a single light receiver, which is arranged at a position at which scattered light output from the sample is received, and is configured to measure an intensity of the scattered light; a sample holder including: a cell having a cavity in which the sample is to be contained; a frame body having a holding space in which the cell is to be arranged, a first opening formed in an incident portion of a first optical path used for at least one measurement of forward measurement or side measurement, in which a scattering angle formed by the incident light and the scattered light is 100° or less, and a second opening formed in an incident portion of a second optical path used for back measurement, in which a scattering angle exceeds 100°; and an optical element having a first surface that forms a certain angle with a side surface of the cavity; and a moving mechanism configured to move the sample holder in a vertical direction, the optical element being arranged in at least one of the incident portion or an exit portion of at least one optical path of the first optical path or the second optical path, the first optical path and the second optical path being separated from each other in the vertical direction, the moving mechanism being configured to move the first opening to a position of the incident portion of the first optical path when the at least one measurement of forward measurement or side measurement is to be performed, and to move the second opening to a position of the incident portion of the second optical path when the back measurement is to be performed. light sources configured to generate incident light to irradiate a sample; a single light receiver, which is arranged at a position at which scattered light output from the sample is received, and is configured to measure an intensity of the scattered light; a sample holder including: a cell having a cavity in which the sample is to be contained; a frame body having a holding space in which the cell is to be arranged, a first opening formed in an incident portion of a first optical path used for at least one measurement of forward measurement or side measurement, in which a scattering angle formed by the incident light and the scattered light is 100° or less, and a second opening formed in an incident portion of a second optical path used for back measurement, in which a scattering angle exceeds 100°; and an optical element having a first surface that forms a certain angle with a side surface of the cavity; and a cell having a cavity in which the sample is to be contained; a frame body having a holding space in which the cell is to be arranged, a first opening formed in an incident portion of a first optical path used for at least one measurement of forward measurement or side measurement, in which a scattering angle formed by the incident light and the scattered light is 100° or less, and a second opening formed in an incident portion of a second optical path used for back measurement, in which a scattering angle exceeds 100°; and an optical element having a first surface that forms a certain angle with a side surface of the cavity; and a moving mechanism configured to move the sample holder in a vertical direction, the optical element being arranged in at least one of the incident portion or an exit portion of at least one optical path of the first optical path or the second optical path, the first optical path and the second optical path being separated from each other in the vertical direction, the moving mechanism being configured to move the first opening to a position of the incident portion of the first optical path when the at least one measurement of forward measurement or side measurement is to be performed, and to move the second opening to a position of the incident portion of the second optical path when the back measurement is to be performed. the optical element being arranged in at least one of the incident portion or an exit portion of at least one optical path of the first optical path or the second optical path, the first optical path and the second optical path being separated from each other in the vertical direction, the moving mechanism being configured to move the first opening to a position of the incident portion of the first optical path when the at least one measurement of forward measurement or side measurement is to be performed, and to move the second opening to a position of the incident portion of the second optical path when the back measurement is to be performed.