Social norms for cooperation are often supported by positive and negative sanctions. Simultaneously, positive interactions in human relationships via sanctions are promoted by positive social behavior. This study investigates the relationship between social behavior and sanctions based on economic laboratory experiments. Participants with unique IDs make decisions on the contribution to public goods, which is inefficient for society. After participating in the public goods game, they decide whether to use the sanctions. The type of sanctions are varied, such as no sanction, only punishable, only rewardable, and all of these are possible. We found that inefficient social behavior increases under conditions where participants can reward each other and that the level of social activity and rewards are positively correlated. To exclude the possibility of the participants misunderstanding inefficiency, we performed an additional experiment that emphasizes the meaning of inefficiency that the contribution toward public goods reduces profits in society as a whole. We found that even with this emphasis, the high level of contributions is sustained when sanctions are possible. A group-level comparison showed that the group that maintained bad norms used the reward option more. Our results suggest that people maintain bad norms in anticipation of positive interaction.