An automatic tool exchanging device for a machine tool, comprising a stopper block (5, 5') attached to a magazine supporting member (2) supporting a magazine (1) at the lower end thereof and capable of swinging to the front and rear, and pulled by an elastic member (8) having one end connected to the upper end of the magazine supporting member (2). Upon arrival of the magazine (1) at a standby position from a tool exchanging position, a stopper (4, 4', 11) is engaged with the stopper block (5, 5') to prevent vibration of the magazine (1). A desired tool among various tools stored in the turret magazine is selected automatically and automatically exchanged for a tool on the machine tool.