An RF coil includes a plurality of concentric loops lying at different positions along a coil axis, whose sensitivity is improved in a central portion, and a plurality of loops are constructed as circular loops whose circles correspond to those formed by cutting a sphere common to the loops vertically with respect to the coil axis at different positions along the coil axis. Each of the plurality of loops constitutes a solenoid coil. Alternatively, a helical coil uninterruptedly running around the coil axis is formed.