In a drive force transmission device, a dry multi-plate clutch is disposed in a closed space for connecting and disconnecting a transmission of drive force. The dry multi-plate clutch includes a drive plate, a driven plate, a frictional face, a front cover and a splash guard. The drive plate is splined to a clutch hub. The driven plate is splined to a clutch drum. The front cover has an air intake port for taking external air into the closed space, and an air venting port for ejecting an air stream from within the closed space to the external air. The splash guard covers the air intake port and the air venting port of the front cover. The splash guard has an opening for drawing in external air through the air intake port and venting an air stream through the air venting port.