The present invention provides a magnetic core and transformer which are reduced in core loss.
The magnetic core according to the present invention comprises a core member which is formed by winding first electrical steel sheets, which is ring shaped seen from a side surface, and which has one or more bent parts seen from a side surface and one or more stacks of second electrical steel sheets stacked together, each the stack being arranged at least at one of the surfaces formed by side surfaces of the first electrical steel sheets at a bent part of the core member so that a surface formed by side surfaces of the second electrical steel sheets runs along it.