A magnet unit for nuclear magnetic resonance, comprising: a plurality of ring-shaped oxide superconducting bulk bodies having a structure in which a RE 2 BaCuO 5 phase is dispersed in a single-crystal REBa 2 Cu 3 O y phase where RE is one or two or more elements selected from rare earth elements, and y satisfies 6.8 ≤ y ≤ 7.1, wherein the plurality of oxide superconducting bulk bodies are coaxially stacked in a coaxial direction to form a stacked body , and the plurality of oxide superconducting bulk bodies include a first oxide superconducting bulk body disposed at one end or both ends of the stacked body , and a second oxide superconducting bulk body adjacent to the first oxide superconducting bulk body , satisfy any one of the following conditions of A), B), A) and B), A) and C), B) and C), and A), B) and C): A) an outer diameter (D QR ) of the first oxide superconducting bulk body is smaller than an outer diameter (D QU ) of the second oxide superconducting bulk body , B) a radial thickness of the first oxide superconducting bulk body is smaller than a radial thickness of the second oxide superconducting bulk body, and C) a volume of the first oxide superconducting bulk body is smaller than a volume of the second oxide superconducting bulk body . a plurality of ring-shaped oxide superconducting bulk bodies having a structure in which a RE 2 BaCuO 5 phase is dispersed in a single-crystal REBa 2 Cu 3 O y phase where RE is one or two or more elements selected from rare earth elements, and y satisfies 6.8 ≤ y ≤ 7.1, wherein the plurality of oxide superconducting bulk bodies are coaxially stacked in a coaxial direction to form a stacked body , and the plurality of oxide superconducting bulk bodies include a first oxide superconducting bulk body disposed at one end or both ends of the stacked body , and a second oxide superconducting bulk body adjacent to the first oxide superconducting bulk body , satisfy any one of the following conditions of A), B), A) and B), A) and C), B) and C), and A), B) and C): A) an outer diameter (D QR ) of the first oxide superconducting bulk body is smaller than an outer diameter (D QU ) of the second oxide superconducting bulk body , B) a radial thickness of the first oxide superconducting bulk body is smaller than a radial thickness of the second oxide superconducting bulk body, and C) a volume of the first oxide superconducting bulk body is smaller than a volume of the second oxide superconducting bulk body . a first oxide superconducting bulk body disposed at one end or both ends of the stacked body , and a second oxide superconducting bulk body adjacent to the first oxide superconducting bulk body , satisfy any one of the following conditions of A), B), A) and B), A) and C), B) and C), and A), B) and C): A) an outer diameter (D QR ) of the first oxide superconducting bulk body is smaller than an outer diameter (D QU ) of the second oxide superconducting bulk body , B) a radial thickness of the first oxide superconducting bulk body is smaller than a radial thickness of the second oxide superconducting bulk body, and C) a volume of the first oxide superconducting bulk body is smaller than a volume of the second oxide superconducting bulk body . A) an outer diameter (D QR ) of the first oxide superconducting bulk body is smaller than an outer diameter (D QU ) of the second oxide superconducting bulk body , B) a radial thickness of the first oxide superconducting bulk body is smaller than a radial thickness of the second oxide superconducting bulk body, and C) a volume of the first oxide superconducting bulk body is smaller than a volume of the second oxide superconducting bulk body . <EOS>