To obtain an ammeter for measuring the current flowing through the element of an electric circuit without connecting the ammeter with the electric circuit by providing first and second connection means connected with a reluctance element in a region of first direction and a region orthogonal thereto.

An element 1 provided on a substrate 5 comprises a thin layer of reluctance material being used to attain the plane Hall effect. The element 1 has regions 2', 2" for allowing connection with a power supply 2 at two end parts thereof along the axis XX'. Furthermore, the element 1 is connected, on the opposite sides thereof, with two connection elements 3', 3" which can be connected with a voltage measuring unit or a resistivity measuring unit 3 along YY' axis extending normally to the axis XX'. When a current flows through a conductor 4, a field is generated in the lateral direction and the magnitude of field induced in a sensor by a measuring current having amplitude I can be determined according to a formula B=(μ0I/πL)*arctan(L/2D), where L is the width of conductor 4, and D is the distance between the conductor 4 and the element 1. The current can be determined based on the magnitude B of field.