In this study, a hoarding tendency is defined as a trait whereby many possessions are saved and cannot be discarded because of their subjective meaning. For this study, an internet-survey of non-clinical individuals was conducted. First, the effects of age and gender on expression of hoarding were investigated. Next, as the main purpose of this study, the causal relationships between hoarding tendencies and various problems that hoarding causes were investigated. Four hundred and fifty-three participants were asked to complete a questionnaire. The main findings were as follows: 1) Females and people in their 30s significantly tended to hoard possessions. 2) The results of analysis indicated that hoarding caused mental problems, economic problems, social problems, and functional problems. In addition, a covariance structure analysis for the proposed model suggested that excessive attachment to possessions, such as “avoidance of discarding possessions” and “extended self,” caused an excessive build-up of items in the home, and these functional problems resulted in the above-mentioned problems. 3) Furthermore, the results of multi-sample simultaneous analysis indicated that the causal model for participants in their 60s was greatly different from that of other age groups. That model revealed that people in their 60s did not hesitate to throw belongings away and did not have the various problems that hoarding causes.