A vehicle data acquisition system configured to acquire vehicle data through an in-vehicle information processing device mounted on a vehicle, and store the acquired vehicle data in a storage device, the in-vehicle information processing device having incorporated therein in advance an information processing section that executes a process procedure of an information processing, the vehicle data acquisition system comprising: a data acquisition assisting section that is configured to be dynamically incorporated in the in-vehicle information processing device so as to assist acquisition of the vehicle data by utilizing an information processing operation state of the in-vehicle information processing device; and a probe section (P1-P9) that is a section of source code arranged as a non-operation instruction at one or a plurality of addresses where data acquiring process included in the process procedure is executed, wherein the probe section (P1-P9) is configured to be capable of being replaced with another instruction in accordance with a command from the data acquisition assisting section, and wherein by being incorporated into the in-vehicle information processing device, the data acquisition assisting section is configured to replace the non-operation instruction of the probe section (P1-P9) with an acquiring instruction for the vehicle data, to store the vehicle data acquired by the replacement acquiring instruction in the storage device in a chronological order, and to re-replace the replacement acquiring instruction of the probe section (P1-P9) with the non-operation instruction after having acquired the necessary vehicle data, the vehicle data acquisition system being characterized in that the probe sections (P1-P9) are arranged at addresses that will be executed and processed in the course of the process procedure, wherein the data acquisition assisting section is configured not to execute the replacement of the instruction in the probe section (P1-P9) when it is predicted that a time required for information processing by the in-vehicle information processing device will exceed a maximum time allocated to the information processing due to executing the replacement of the instruction in the probe section (P1-P9), the maximum time being required for one execution in periodically executing the process procedure. a data acquisition assisting section that is configured to be dynamically incorporated in the in-vehicle information processing device so as to assist acquisition of the vehicle data by utilizing an information processing operation state of the in-vehicle information processing device; and a probe section (P1-P9) that is a section of source code arranged as a non-operation instruction at one or a plurality of addresses where data acquiring process included in the process procedure is executed, wherein the probe section (P1-P9) is configured to be capable of being replaced with another instruction in accordance with a command from the data acquisition assisting section, and wherein by being incorporated into the in-vehicle information processing device, the data acquisition assisting section is configured to replace the non-operation instruction of the probe section (P1-P9) with an acquiring instruction for the vehicle data, to store the vehicle data acquired by the replacement acquiring instruction in the storage device in a chronological order, and to re-replace the replacement acquiring instruction of the probe section (P1-P9) with the non-operation instruction after having acquired the necessary vehicle data, the vehicle data acquisition system being characterized in that the probe sections (P1-P9) are arranged at addresses that will be executed and processed in the course of the process procedure, wherein the data acquisition assisting section is configured not to execute the replacement of the instruction in the probe section (P1-P9) when it is predicted that a time required for information processing by the in-vehicle information processing device will exceed a maximum time allocated to the information processing due to executing the replacement of the instruction in the probe section (P1-P9), the maximum time being required for one execution in periodically executing the process procedure.