To provide a belt type continuous variable transmission miniaturized by reducing a center distance between driving pulley and a driven pulley by an improved belt tension structure of the belt type continuous variable transmission having a double split pulley structure.

Each of a driving pulley 7 and driven pulley 8 is constituted of a split pulley in which a belt winding radius can be extended and reduced. A speed change operating mechanism is provided, which contrarily ensures an adjustable extension or reduction of a perspective distance of each of the movable pulley pieces 7B, 8B in a linkage manner to each of the stationary pulley pieces 7A, 8A while a wound length of the belt 16 wound around both pulleys 7, 8 is kept at constant. A forcing mechanism E is provided on the driven pulley 8, which mechanism E utilizes a wound spring 30 which always forces the movable pulley piece 8B, toward the stationary pulley piece 8A side, to an operating member 17 which can move at perspective the movable pulley piece 8B.