A coil component includes an insulator part and a coil part. The insulator part is constituted by an electrical insulation material, and is no more than 600 μm long and no more than 600 μm high. The coil part is wound around one axis and placed inside the insulator part. The coil part has an opening part constituted by straight line parts and curved line parts and whose shape as viewed from the one axis direction is an approximate quadrangle, wherein the line length of the curved line parts along the inner periphery of the opening part is 20% or more but no more than 40% of the line length of the inner periphery of the opening part. The coil component can satisfy both a size reduction need and the properties need.