The present study explored the effects of two types of interpersonal trust: general trust and specific trust, on cooperative choices in two-person Prisoner's Dilemma Game, and examined the role of pre-experimental communication in development of trust. An experiment revealed the following results: (1) The effects of two types of trust were contingent upon opportunity for communication; general trust enhanced cooperative choice behavior in the prior interaction condition while specific trust enhanced it in the communication condition. (2) Communication type strongly affected specific trust towards the partner with whom communication had taken place. (3) Uncooperative communication contributed to the cooperation rates indirectly through specific trust towards the communicated partner, whereas cooperative communication explained the cooperation rates directly. It was found that communication opportunity itself did not affect cooperation directly, but it determined which type of trust came into operation. The possibility of specific trust becoming generalized toward general trust was discussed.