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.