Considering the practical use of geopolymer concrete, it is highly essential to comprehensively understand its time-dependent deformation characteristics such as shrinkage and creep, and to establish a prediction method. In this study, shrinkage measurements and compressive creep tests of fly ash-based geopolymer concrete with various mix proportions and curing methods were conducted. The starting age of the loading for the compressive creep test is 6 days. In addition, compression test, analysis of pore size distribution, and comparisons with creep prediction of cement concrete were carried out to elucidate the characteristics and mechanisms of shrinkage and creep of geopolymer concrete. The 7 days compressive strengths of heated and sealed specimens were 37.7 N/mm2 and 37.4 N/mm2 for 0.9 and 0.7 liquid to powder ratio, respectively. The creep coefficients of these specimens at 150 days after loading were 0.70 and 0.71, respectively, implying that liquid to powder ratio had no significant effect on creep. On the other hand, the compressive strength of specimen sealed cured for 7 days of age at 20° C was 16.8 N/mm2. The creep coefficient of this specimen at 150 days after loading was about 3.10, suggesting that compressive strength and pore structure influence creep. The results also point out that the rate of increase in creep coefficient of geopolymer concrete converges relatively rapid compared to cement concrete.