Do you have to hold your Arcane Focus?

Question

Hear from a lot of people that to cast a spell you need to hold your arcane focus in your hand. However scouring the books and any errata I can't seem to find anything actually stated officially here.

Does anyone have an actual source for this? Can it not be something just on their person?

So far only the holy symbol states that it must be held in your hand, does this mean that the others don't?

Answer 1

Yes.

You need to hold the arcane focus for it to substitute as a material component.

Spellcasting Focus Substitutes for a Material Component

To clarify: you only need to hold a spellcasting focus to cast spells with a material component, not for every spell. You can tell the difference in the spell description. Two examples, one without (Magic Missile) and one with (Major Image) a material component.

Spell Examples

Magic Missile
1st-level evocation
Casting Time: 1 action
Range: 120 feet
Components: V, S
Duration: Instantaneous

Major Image
3rd-level illusion
Casting Time: 1 action
Range: 120 feet
Components: V, S, M (a bit of fleece)
Duration: Concentration, up to 10 minutes (Basic Rules p. 96)

Spellcasting Rules

From the spellcasting rules in Chapter 10.

Material (M)
Casting some spells requires particular objects, specified in parentheses in the component entry. A character can use a component pouch or a spellcasting focus (found in chapter 5) in place of the components specified for a spell. {snip} A spellcaster must have a hand free to access these components—or to hold a spellcasting focus—but it can be the same hand that he or she uses to perform somatic components. (Basic Rules p. 79)

Spellcasting Focus

A spellcasting focus is:

• A Holy Symbol (Basic Rules p. 48.)
• A Druidic Focus (Basic Rules p. 48.)
• An Arcane Focus (Basic Rules p. 47.)

Note on the Holy Symbol:

A cleric or paladin can use a holy symbol as a spellcasting focus, as described in chapter 10. To use the symbol in this way, the caster must hold it in hand, wear it visibly, or bear it on a shield.

The Fine Print

The specific exceptions to this general rule are spells that have a material component that is consumed. Example: Resurrection.

Resurrection
7th-level necromancy
Casting Time: 1 hour
Range: Touch
Components: V, S, M (a diamond worth at least 1,000 gp, which the spell consumes)
Duration: Instantaneous (Basic Rules p. 99)

(Finer print: A spell with a material component that isn't consumed but has a specific cost in GP (example is Identify, requires a pearl worth at least 100 gp which isn't consumed) still needs the material component).

The same rules are in the PHB.

Note: we had a discussion on what constitutes a bardic spellcasting focus here.