Edit in JSFiddle

//sourceの設定
var osmsource = new ol.source.OSM();

//Layerの設定
var osmlayer = new ol.layer.TileLayer({
  source : osmsource
});

//View2Dの設定
var viewoption = new ol.View2D({
  //projection: 'EPSG:3857',
  center: ol.proj.transform([139.5, 35.4], 'EPSG:4326', 'EPSG:3857'),
  zoom : 8
});

//Scalelineの設定(m単位)
var scalecontrol = ol.control.defaults({}, [
  new ol.control.ScaleLine({
    units: ol.control.ScaleLineUnits.METRIC
  })
]);

//mapの設定
var map = new ol.Map({
  controls: scalecontrol,
  layers : [osmlayer],
  target : 'map_element',
  view : viewoption
});

//Zoomsliderの設定
var zoomslider = new ol.control.ZoomSlider({
  map: map
});
<title>My OpenLayers Map</title>
<div id='map_element' style='width: 600px; height: 480px;'></div>

              

External resources loaded into this fiddle: