1. An LC device comprising:a planar element having first and second principal surfaces that oppose each other with an insulating resin layer disposed between at least a portion of the first and second principal surfaces;
an inductor disposed inside the planar element and including a loop-shaped conductor pattern in a plan view from the first principal surface;
a mounting-type capacitor disposed in an opening of the loop-shaped conductor pattern in the plan view and inside the planar element with at least a mounting surface of the capacitor in contact with the insulating resin layer; and
a first magnetic-body that forms a portion of the planar element and that is disposed between the loop-shaped conductor pattern of the inductor and the mounting-type capacitor over an entire length of the loop-shaped conductor pattern.