A magnetic resonance imaging apparatus comprising processing circuitry configured: to obtain biological information about cyclic movements of a subject to be imaged; to measure a duration of one cycle of the cyclic movements of the subject to be imaged on a basis of the obtained biological information; to set a rotation angle (5a, 5b, 5c) of a non-Cartesian trajectory in a k-space on a basis of the measured duration of one cycle of the cyclic movements of the subject to be imaged; to acquire k-space data comprising a plurality of lines (3, 4, 7a, 7b, 7c, 8a, 8b) of the non-Cartesian trajectory by rotating the non-Cartesian trajectory at the set rotation angle (5a, 5b, 5c); and to generate an image by reconstructing the k-space data, wherein the processing circuitry is configured to calculate the quantity of lines (3, 4, 7a, 7b, 7c, 8a, 8b) of the non-Cartesian trajectory acquired at one cycle of the cyclic movements as a product of the duration of the cycle of the cyclic movements and the number of lines of the trajectory acquired per unit of time and to evaluate a value of an index indicating dispersiveness of the to be acquired lines of the non-Cartesian trajectory extracted from a specified temporal phase of the cyclic movements, wherein the value of the index is calculated as: π 2 P ∑ i = 0 P − 1 Δ φ i 2 where P denotes the number of lines subject to the data acquisitions and Δφi denotes the angle difference between an i-th line and an (i+1)th line when the lines subject to the acquisitions in the sampling with the rotation angle are sorted according to the magnitudes of the angles formed with an initial line serving as a reference, the value of the index being calculated for a plurality of quantities of lines (3, 4, 7a, 7b, 7c, 8a, 8b) of the non-Cartesian trajectory acquired at one cycle of the cyclic movements in a range having the calculated quantity of lines (3, 4, 7a, 7b, 7c, 8a, 8b) of the non-Cartesian trajectory acquired at one cycle of the cyclic movements as a center, wherein the processing circuitry is configured to select, as for the k-space data to be acquired at one cycle of the cyclic movements, the rotation angle, from among a plurality of rotation angles, such as to maximize an average of the values of the index in said range. to obtain biological information about cyclic movements of a subject to be imaged; to measure a duration of one cycle of the cyclic movements of the subject to be imaged on a basis of the obtained biological information; to set a rotation angle (5a, 5b, 5c) of a non-Cartesian trajectory in a k-space on a basis of the measured duration of one cycle of the cyclic movements of the subject to be imaged; to acquire k-space data comprising a plurality of lines (3, 4, 7a, 7b, 7c, 8a, 8b) of the non-Cartesian trajectory by rotating the non-Cartesian trajectory at the set rotation angle (5a, 5b, 5c); and to generate an image by reconstructing the k-space data, wherein the processing circuitry is configured to calculate the quantity of lines (3, 4, 7a, 7b, 7c, 8a, 8b) of the non-Cartesian trajectory acquired at one cycle of the cyclic movements as a product of the duration of the cycle of the cyclic movements and the number of lines of the trajectory acquired per unit of time and to evaluate a value of an index indicating dispersiveness of the to be acquired lines of the non-Cartesian trajectory extracted from a specified temporal phase of the cyclic movements, wherein the value of the index is calculated as: π 2 P ∑ i = 0 P − 1 Δ φ i 2 where P denotes the number of lines subject to the data acquisitions and Δφi denotes the angle difference between an i-th line and an (i+1)th line when the lines subject to the acquisitions in the sampling with the rotation angle are sorted according to the magnitudes of the angles formed with an initial line serving as a reference, the value of the index being calculated for a plurality of quantities of lines (3, 4, 7a, 7b, 7c, 8a, 8b) of the non-Cartesian trajectory acquired at one cycle of the cyclic movements in a range having the calculated quantity of lines (3, 4, 7a, 7b, 7c, 8a, 8b) of the non-Cartesian trajectory acquired at one cycle of the cyclic movements as a center, wherein where P denotes the number of lines subject to the data acquisitions and Δφi denotes the angle difference between an i-th line and an (i+1)th line when the lines subject to the acquisitions in the sampling with the rotation angle are sorted according to the magnitudes of the angles formed with an initial line serving as a reference, the value of the index being calculated for a plurality of quantities of lines (3, 4, 7a, 7b, 7c, 8a, 8b) of the non-Cartesian trajectory acquired at one cycle of the cyclic movements in a range having the calculated quantity of lines (3, 4, 7a, 7b, 7c, 8a, 8b) of the non-Cartesian trajectory acquired at one cycle of the cyclic movements as a center, wherein the processing circuitry is configured to select, as for the k-space data to be acquired at one cycle of the cyclic movements, the rotation angle, from among a plurality of rotation angles, such as to maximize an average of the values of the index in said range.