This study investigated the effects of reputation-making norms on personal network size. Someone who behaved cooperatively/non-cooperatively toward a “bad” person is denoted as C to B/D to B. Reputation-making norms are then defined by a combination of the assessment of C to B and the assessment of D to B. We hypothesized that (1) those who judge C to B negatively would form smaller personal networks than those who judge C to B positively, and (2) those who judge D to B negatively would form smaller personal networks than those who judge D to B positively. We used scenarios to assess the internalized reputation-making norms as an independent variable and investigated their effects on the size of participants' support networks as a dependent variable. Results indicated that the size of the support networks of participants following a norm which does not permit C to B was smaller than that of participants following a norm which does permit C to B. These findings suggest that using reputation made by norms which do not permit spoiling narrows the size of cooperative relationships.