The invention provides a solenoid coil in which a sensitive area is expanded by increasing a homogeneity of a static magnetic field in an outer side from a solenoid coil end so as to be capable of receiving a signal from a space in an outer side from the coil end. A static magnetic field compensating member is arranged in such a manner as to extend a main solenoid coil in an axial direction, and the static magnetic field compensating member is structured such as not to generate a high-frequency magnetic field in such a direction as to cancel a high-frequency magnetic field generated by the main solenoid coil. Specifically, a ring-shaped material constituted by an insulant having a magnetic susceptibility of the same sign as a material of the main solenoid coil is arranged in an outer side in an axial direction of the main solenoid in such a manner as to come into contact with the main solenoid coil. Further, a C-shaped member or a ring-shaped member cut into a plurality of sections in a circumferential direction is arranged in the outer side in the axial direction of the main solenoid coil in such a manner as not to come into contact with the main solenoid coil.