A support structure for a crankshaft comprising: a cylinder block of an internal combustion engine; a crankshaft that is rotatably supported on the cylinder block and has an end portion protruding from the cylinder block; a sprocket that is attached on the end portion protruding from the cylinder block and is connectable to a cam shaft; a pulley that is attached on the end portion on an opposite side from the sprocket with respect to the cylinder block and is connectable to an auxiliary apparatus; an end bearing that rotatably supports the end portion relative to the cylinder block and is provided on the end portion between the sprocket and the pulley; a chain case that is attached to the cylinder block to cover the end portion of the crankshaft to which the sprocket is attached; characterised in that the support structure further comprises: a lubricating oil pump that is driven by rotation of the crankshaft to pump the lubricating oil to a lubricating oil path of the internal combustion engine; a bearing supply path that supplies the lubricating oil pumped by driving of the lubricating oil pump to the end bearing; and an oil seal configured to seal the end portion of the crankshaft, wherein the lubricating oil pump is disposed on the end portion of the crankshaft inside of the chain case and arranged outside of the sprocket, the outside being the side opposite to the cylinder block, wherein the lubricating oil pump is disposed to be adjacent to the end bearing, wherein the end bearing is supplied with the lubricating oil from the lubricating oil pump, wherein the end bearing is attached to an inside of the chain case, the inside being a side where the chain case faces the cylinder block. a cylinder block of an internal combustion engine; a crankshaft that is rotatably supported on the cylinder block and has an end portion protruding from the cylinder block; a sprocket that is attached on the end portion protruding from the cylinder block and is connectable to a cam shaft; a pulley that is attached on the end portion on an opposite side from the sprocket with respect to the cylinder block and is connectable to an auxiliary apparatus; an end bearing that rotatably supports the end portion relative to the cylinder block and is provided on the end portion between the sprocket and the pulley; a chain case that is attached to the cylinder block to cover the end portion of the crankshaft to which the sprocket is attached; characterised in that the support structure further comprises: a lubricating oil pump that is driven by rotation of the crankshaft to pump the lubricating oil to a lubricating oil path of the internal combustion engine; a bearing supply path that supplies the lubricating oil pumped by driving of the lubricating oil pump to the end bearing; and an oil seal configured to seal the end portion of the crankshaft, wherein the lubricating oil pump is disposed on the end portion of the crankshaft inside of the chain case and arranged outside of the sprocket, the outside being the side opposite to the cylinder block, wherein the lubricating oil pump is disposed to be adjacent to the end bearing, wherein the end bearing is supplied with the lubricating oil from the lubricating oil pump, wherein the end bearing is attached to an inside of the chain case, the inside being a side where the chain case faces the cylinder block. a lubricating oil pump that is driven by rotation of the crankshaft to pump the lubricating oil to a lubricating oil path of the internal combustion engine; a bearing supply path that supplies the lubricating oil pumped by driving of the lubricating oil pump to the end bearing; and an oil seal configured to seal the end portion of the crankshaft, wherein the lubricating oil pump is disposed on the end portion of the crankshaft inside of the chain case and arranged outside of the sprocket, the outside being the side opposite to the cylinder block, wherein the lubricating oil pump is disposed to be adjacent to the end bearing, wherein the end bearing is supplied with the lubricating oil from the lubricating oil pump, wherein the end bearing is attached to an inside of the chain case, the inside being a side where the chain case faces the cylinder block.