Sub ExportTrueArcs2Shapefile()

  Dim pDoc As IMxDocument
  Dim pFlayerGDB As IFeatureLayer
  Dim pFCursor As IFeatureCursor
  Dim pFeature As IFeature
  Dim pFlayerShape As IFeatureLayer
  Dim pFlayerShapeFC As IFeatureClass
  Dim pPolycurve As IPolycurve2
  Dim dPi As Double
  Dim dMaxSeg As Double
  Dim pGeometry As IGeometry
  Dim dXyUnit As Double
  Dim dXfalse As Double
  Dim dyFalse As Double
  Dim pSPRef As ISpatialReference
  Dim pSegCol As ISegmentCollection
  Dim bNonLinear As Boolean
  Dim pCurve As ICurve

  Set pDoc = ThisDocument
  Set pFlayerGDB = pDoc.FocusMap.Layer(0)
  Set pFCursor = pFlayerGDB.FeatureClass.Search(Nothing, False)
  Set pFeature = pFCursor.NextFeature

  If pFlayerGDB.FeatureClass.ShapeType <> esriGeometryPolygon Then Exit Sub

  Set pFlayerShape = pDoc.FocusMap.Layer(1)
  Set pFlayerShapeFC = pFlayerShape.FeatureClass

  'ラジアンで角度を取得します。
  dPi = Atn(1) * 4

  Set pGeometry = pFeature.ShapeCopy
  Set pSPRef = pGeometry.SpatialReference
  pSPRef.GetFalseOriginAndUnits dXfalse, dyFalse, dXyUnit

  dMaxSeg = (1 / dXyUnit) * 100000

  While Not pFeature Is Nothing
    Set pCurve = pFeature.Shape
    Set pPolycurve = pCurve
    Set pSegCol = pPolycurve
    pSegCol.HasNonLinearSegments bNonLinear
    If bNonLinear Then
      pPolycurve.DensifyByAngle dMaxSeg, dPi / 180
    End If
    storeFeature pPolycurve, pFlayerShapeFC
    Set pFeature = pFCursor.NextFeature
  Wend

End Sub

Private Sub storeFeature(pGeo As IGeometry, pFClass As IFeatureClass)

On Error GoTo errHand

  Dim pNewFCursor As IFeatureCursor
  Dim pFeatureBuffer As IFeatureBuffer

  Set pNewFCursor = pFClass.Insert(True)
  Set pFeatureBuffer = pFClass.CreateFeatureBuffer
  Set pFeatureBuffer.Shape = pGeo
  pNewFCursor.InsertFeature pFeatureBuffer
  pNewFCursor.Flush
  Exit Sub

errHand:
  Debug.Print Err.Description

End Sub