A belt conveyor comprising a telescopic frame (1), an endless conveyor belt (9) which is supported by idlers (12) connected to the frame (1), a drawing drum (10), and a tilting drum (11), via which the conveyor belt (9) is arranged to run, and an actuator (14) mounted to the frame (1) for changing the length of the frame (1). The frame of the belt conveyor comprises frame blocks (5a, 5b, 5c, 5d, 5e, 5f, 5g) installed to each other in a slidable manner and a lattice mechanism (20) installed to them in a pivotal manner to effect a change in the length of the belt conveyor as a result of the operation of the actuator (14). The frame blocks (5a, 5b, 5c, 5d, 5e, 5f, 5g) comprise at least one frame pipe (2a, 2b, 2c, 2d, 2e, 2f, 2g, 3a, 3b, 3c, 3d, 3e, 3f, 3g), wherein at least one frame block (5a, 5b, 5c, 5d, 5e, 5f, 5g) comprises a supporting beam (4a, 4b, 4b′ 4c, 4d, 4d′, 4e, 4f, 4g) connected to at least one frame pipe (2a, 2b, 2c, 2d, 2e, 2f, 2g, 3a, 3b, 3c, 3d, 3e, 3f, 3g).