A tooth contact position adjustment amount estimation device that performs processing with respect to estimating a tooth contact position adjustment amount for dimensional data of parts constituting a power transmission mechanism according to the present invention, comprising: a machine learning device that performs processing with respect to estimating the tooth contact position adjustment amount for the dimensional data of parts constituting the power transmission mechanism, wherein the machine learning device observes part dimensional data, which is the dimensional data of parts constituting the power transmission mechanism, as a state variable indicating a current state of an environment, and performs processing with respect to estimating the tooth contact position adjustment amount for the dimensional data of parts constituting the power transmission mechanism in assembling the power transmission mechanism by performing processing with respect to machine learning based on the observed state variable.