The operation data collection device for work machines includes a plurality of sensors attached to a work machine to receive measurement data as operation data and record the operation data in an operation data storage section. The operation data collection device further includes: a communication processing section that transmits the operation data stored in the operation data storage section to an external server in response to a download request from the external server; an access history management section that manages a download status of the operation data recorded in the operation data storage section, through the download request from the external server and the transmission of the operation data to the external server; and a recorded data change processing section that changes a condition for recording the operation data in the operation data storage section in accordance with the download status of the operation data.