Yes. It's only natural as your body consumes food and water then passes it out again.
There are two ways to avoid these fluctuations as much as possible if you want to keep weighing yourself. You can weigh yourself at the same time each day, for instance before breakfast so that there isn't much food in your system to influence the reading. Even then, fluid retention, constipation or dehydration can make your weight fluctuate from day to day. You can avoid these fluctuations by only weighing yourself once per week. However that still won't avoid all fluctuations! You'll retain water more in hot weather, and women retain water the week before TTOTM. Weighing yourself once per month would avoid most fluctuations, however it would also miss any gradual weight gain so it might not suit some people. Make sure you wear exactly the same clothes (or lack thereof) when you weigh yourself. Clothing can contribute over a kilo to the scales so different outfits will alter your reading!
When I'm weighing myself I tend to weigh every day at the same time (before breakfast) and just note trends rather than take each day as gospel. If you're 76 kilos give or take a hundred grams for most of the week except for one day where you're suddenly 77.5 kilos it's almost guaranteed that one day is simply an aberration and your weight will go back to normal the following day. If, however, your weight is steadily increasing by 100g every couple of days then it should be taken as a warning sign!
A better way for measuring weight loss is to use a measuring tape or simply judge by how loose your clothes are getting. This has the added advantage of not being confused by muscle gain. Muscle is denser than fat so you could lose fat, gain muscle, be a little smaller yet still weigh the same!