A pair of 8-shaped coils vertically sandwiches an object to be examined for providing a magnetic field in the horizontal direction perpendicular to the body axis in the object. A pair of rectangular coils also vertically sandwiches the object for providing a magnetic field in the vertical direction in the object. The pair of 8-shaped coils is connected for detecting a first magnetic resonance signal from the object and the pair of rectangular coils is connected for detecting a second magnetic resonance signal from the object. A phase of one of an output of the pair of 8-shaped coils and an output of the pair of rectangular coils is shifted by 90.degree. and summing a shifted output and the other output. An upper coil assembly of the 8-shaped coil pair and the rectangular coil pair is connected to a lower coil assembly at one end thereof in the lateral direction of the object and is pivotal to be freely opened and closed. To mount the coil assembly to the object, the upper coil assembly is opened, the object is placed on the lower coil assembly, and the upper coil assembly is closed.