The present invention aims to be able to prevent excess heat release of a busbar and to be able to cause a current detection device that detects current flowing through the busbar to be more compact by adopting a small magnetic core. The current detection device (1) is provided with a current detection busbar (30). The current detection busbar (30) comprises a conductor from which are formed: a first section (31) that penetrates the central opening (11) of the magnetic core (10) along a first direction, which is the direction of passage of current; and a plate-shaped second section (32) that is continuous with the first section (31) at both sides in the first direction. The width (D5) of the second section (32) is formed greater than the maximum width (D3) of the central opening (11) of the magnetic core (10), and the minimum width (D4) of the contour of a cross section of the first section (31) is formed greater than the thickness (D6) of the second section (32). The magnetic core (10), the current detection busbar (30) and a hole element (20) are held in a mutually non-contacting state by means of an insulating casing (40).